Pub Date : 2011-03-10DOI: 10.2174/1874378101105010001
P. K. Bhunya
The present study critically reviews the synthetic unit hydrograph (SUH) methods available in hydrologic lit- erature. The study reveals that the traditional methods of SUH derivation, e.g., Snyder, SCS, traditional methods like Sny- der and TS method that does not yield satisfactory results, and their application to the practical engineering problems is tedious and combursome. On the other hand, probability distribution functions (pdfs) based SUH methods are easy to ap- ply, and easily meet the UH criterion, i.e. the area under the curve is unity, and rely on a stronger mathematical base and sounder hydrologic perception. The recent pdfs used for deriving UHs in ungauged catchments, address the SUH shapes with more flexibility than the earlier pdfs proposed by (1) for SUH derivation.
{"title":"Synthetic Unit Hydrograph Methods: A Critical Review","authors":"P. K. Bhunya","doi":"10.2174/1874378101105010001","DOIUrl":"https://doi.org/10.2174/1874378101105010001","url":null,"abstract":"The present study critically reviews the synthetic unit hydrograph (SUH) methods available in hydrologic lit- erature. The study reveals that the traditional methods of SUH derivation, e.g., Snyder, SCS, traditional methods like Sny- der and TS method that does not yield satisfactory results, and their application to the practical engineering problems is tedious and combursome. On the other hand, probability distribution functions (pdfs) based SUH methods are easy to ap- ply, and easily meet the UH criterion, i.e. the area under the curve is unity, and rely on a stronger mathematical base and sounder hydrologic perception. The recent pdfs used for deriving UHs in ungauged catchments, address the SUH shapes with more flexibility than the earlier pdfs proposed by (1) for SUH derivation.","PeriodicalId":247243,"journal":{"name":"The Open Hydrology Journal","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130628141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-12-30DOI: 10.2174/1874378101004010184
R. K. Rai, A. Upadhyay, C. Ojha
Identification of the precise nature and attributes of the time series of climatological data is very important and is usually the first step for water resources planning and management. Such exercise is very important for hydro-climatic extremes. In many instances, a climatic time series is generally not statistically independent but is comprised of patterns of persistence, cycles, trends or some other non-random components. To see the importance of the subject, this paper de- scribes the statistical approach used to investigate the presence and extent of persistence, trend and periodicity in climatic time series. The methodology was applied to investigate the spatial distribution pattern of the indicative hydro-climatic variables over the Yamuna River basin of India. Hydro-climatic time series used in the analysis were annual rainfall; Monsoon and Non-monsoon rainfall; annual, Monsoon and Non-monsoon rainydays; onset of effective monsoon; and aridity index.
{"title":"Temporal variability of climatic parameters of Yamuna River basin: spatial analysis of persistence, trend and periodicity.","authors":"R. K. Rai, A. Upadhyay, C. Ojha","doi":"10.2174/1874378101004010184","DOIUrl":"https://doi.org/10.2174/1874378101004010184","url":null,"abstract":"Identification of the precise nature and attributes of the time series of climatological data is very important and is usually the first step for water resources planning and management. Such exercise is very important for hydro-climatic extremes. In many instances, a climatic time series is generally not statistically independent but is comprised of patterns of persistence, cycles, trends or some other non-random components. To see the importance of the subject, this paper de- scribes the statistical approach used to investigate the presence and extent of persistence, trend and periodicity in climatic time series. The methodology was applied to investigate the spatial distribution pattern of the indicative hydro-climatic variables over the Yamuna River basin of India. Hydro-climatic time series used in the analysis were annual rainfall; Monsoon and Non-monsoon rainfall; annual, Monsoon and Non-monsoon rainydays; onset of effective monsoon; and aridity index.","PeriodicalId":247243,"journal":{"name":"The Open Hydrology Journal","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126580320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-12-30DOI: 10.2174/1874378101004010173
M. Vithanage, K. Villholth, P. Engesgaard, K. Jensen
Groundwater is the only source of water for domestic as well as agricultural purposes in the sand aquifer in be- tween sea and lagoon configuration typically found in the eastern Sri Lanka. This study was carried out to estimate the safe yield and assess the vulnerability of the sandy aquifer on the eastern coastal belt of Sri Lanka by rapid urbanization, agriculture and as well as climate change. A typical aquifer system was modeled as a part of a synthetic study to under- stand the sustainability of these coastal aquifers based on the observations made through a pilot field site in the eastern coastal sand stretch in Sri Lanka. Two dimensional model simulations were carried out representing 2000 m length, 22 m deep and 2 m wide model domain respectively. The safe yield of the aquifer is estimated to be 0.37 m 3 /m 2 for an average hydrological year and 0.18 m 3 /m 2 for a dry hydrological year. Water balance in the aquifer system is in equilibrium with the present recharge. However, it is important that the wells to be placed at least 750 m inland from the sea and lagoon re- spectively to avoid salt and brackish water intrusion. According to the modeling results, currently the aquifer system shows no signs of depletion or sea water intrusion. However, increase of population, increase of pumping, and reduction of recharge due to climate change can increase the aquifer vulnerability for contamination by salt and brackish water.
{"title":"Vulnerability analysis of the coastal sandy aquifers in the east coast of Sri Lanka with recharge change consideration.","authors":"M. Vithanage, K. Villholth, P. Engesgaard, K. Jensen","doi":"10.2174/1874378101004010173","DOIUrl":"https://doi.org/10.2174/1874378101004010173","url":null,"abstract":"Groundwater is the only source of water for domestic as well as agricultural purposes in the sand aquifer in be- tween sea and lagoon configuration typically found in the eastern Sri Lanka. This study was carried out to estimate the safe yield and assess the vulnerability of the sandy aquifer on the eastern coastal belt of Sri Lanka by rapid urbanization, agriculture and as well as climate change. A typical aquifer system was modeled as a part of a synthetic study to under- stand the sustainability of these coastal aquifers based on the observations made through a pilot field site in the eastern coastal sand stretch in Sri Lanka. Two dimensional model simulations were carried out representing 2000 m length, 22 m deep and 2 m wide model domain respectively. The safe yield of the aquifer is estimated to be 0.37 m 3 /m 2 for an average hydrological year and 0.18 m 3 /m 2 for a dry hydrological year. Water balance in the aquifer system is in equilibrium with the present recharge. However, it is important that the wells to be placed at least 750 m inland from the sea and lagoon re- spectively to avoid salt and brackish water intrusion. According to the modeling results, currently the aquifer system shows no signs of depletion or sea water intrusion. However, increase of population, increase of pumping, and reduction of recharge due to climate change can increase the aquifer vulnerability for contamination by salt and brackish water.","PeriodicalId":247243,"journal":{"name":"The Open Hydrology Journal","volume":"286 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115292346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-12-30DOI: 10.2174/1874378101004010122
C. Ojha, M. Goyal, A. Adeloye
In this paper, downscaling models are developed using a Linear Multiple Regression (LMR) and Artificial Neural Networks (ANNs) for obtaining projections of mean monthly precipitation to lake-basin scale in an arid region in India. The effectiveness of these techniques is demonstrated through application to downscale the predictand (precipita- tion) for the Pichola lake region in Rajasthan state in India, which is considered to be a climatically sensitive region. The predictor variables are extracted from (1) the National Centers for Environmental Prediction (NCEP) reanalysis dataset for the period 1948-2000, and (2) the simulations from the third-generation Canadian Coupled Global Climate Model (CGCM3) for emission scenarios A1B, A2, B1 and COMMIT for the period 2001-2100. The scatter plots and cross- correlations are used for verifying the reliability of the simulation of the predictor variables by the CGCM3. The perform- ance of the linear multiple regression and ANN models was evaluated based on several statistical performance indicators. The ANN based models is found to be superior to LMR based models and subsequently, the ANN based model is applied to obtain future climate projections of the predictand (i.e precipitation). The precipitation is projected to increase in future for A2 and A1B scenarios, whereas it is least for B1 and COMMIT scenarios using predictors. In the COMMIT scenario, where the emissions are held the same as in the year 2000.
{"title":"Downscaling of Precipitation for Lake Catchment in Arid Region in India using Linear Multiple Regression and Neural Networks","authors":"C. Ojha, M. Goyal, A. Adeloye","doi":"10.2174/1874378101004010122","DOIUrl":"https://doi.org/10.2174/1874378101004010122","url":null,"abstract":"In this paper, downscaling models are developed using a Linear Multiple Regression (LMR) and Artificial Neural Networks (ANNs) for obtaining projections of mean monthly precipitation to lake-basin scale in an arid region in India. The effectiveness of these techniques is demonstrated through application to downscale the predictand (precipita- tion) for the Pichola lake region in Rajasthan state in India, which is considered to be a climatically sensitive region. The predictor variables are extracted from (1) the National Centers for Environmental Prediction (NCEP) reanalysis dataset for the period 1948-2000, and (2) the simulations from the third-generation Canadian Coupled Global Climate Model (CGCM3) for emission scenarios A1B, A2, B1 and COMMIT for the period 2001-2100. The scatter plots and cross- correlations are used for verifying the reliability of the simulation of the predictor variables by the CGCM3. The perform- ance of the linear multiple regression and ANN models was evaluated based on several statistical performance indicators. The ANN based models is found to be superior to LMR based models and subsequently, the ANN based model is applied to obtain future climate projections of the predictand (i.e precipitation). The precipitation is projected to increase in future for A2 and A1B scenarios, whereas it is least for B1 and COMMIT scenarios using predictors. In the COMMIT scenario, where the emissions are held the same as in the year 2000.","PeriodicalId":247243,"journal":{"name":"The Open Hydrology Journal","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126932791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-12-30DOI: 10.2174/1874378101004010137
R. Nawaz, T. Bellerby, M. Sayed, M. Elshamy
gypt Abstract: This study describes implementation of hydrological climate change impact assessment t ool utilising a combi- nation of statistical spatiotemporal downscaling and an operational hydrological model known as the Nile Forecasting System. A spatial rainfall generator was used to produce high-resolution (daily , 20km) gridded rainfall data required by the distributed hydrological model from monthly GCM outputs. The combined system was used to assess the sensitivity of upper Blue Nile flows at Diem flow gauging station to changes in future rainfall during th e June-September rainy sea- son based on output from three GCMs. The assessment also incorporated future evapotra nspiration changes over the ba- sin. The climate change scenarios derived in this study were broadly in line with other studies, with the majority of scenar- ios indicating wetter conditions in the future. Translating the impacts in to runoff in the basin showed increased future mean flows, although these would be offset to some degree by rising evapotranspiration. I mpacts on extreme runoff indi- cated the possibility of more severe fl oods in future. These are likely to be exacerbated by land-use changes including overgrazing, deforestation, and improper farming practices. Blue Nile basin flood managers the refore need to continue to prepare for the possibility of more frequent floods by adopting a range of measures to mi nimise loss of life and guard against other flood damage.
{"title":"Blue Nile Runoff Sensitivity to Climate Change","authors":"R. Nawaz, T. Bellerby, M. Sayed, M. Elshamy","doi":"10.2174/1874378101004010137","DOIUrl":"https://doi.org/10.2174/1874378101004010137","url":null,"abstract":"gypt Abstract: This study describes implementation of hydrological climate change impact assessment t ool utilising a combi- nation of statistical spatiotemporal downscaling and an operational hydrological model known as the Nile Forecasting System. A spatial rainfall generator was used to produce high-resolution (daily , 20km) gridded rainfall data required by the distributed hydrological model from monthly GCM outputs. The combined system was used to assess the sensitivity of upper Blue Nile flows at Diem flow gauging station to changes in future rainfall during th e June-September rainy sea- son based on output from three GCMs. The assessment also incorporated future evapotra nspiration changes over the ba- sin. The climate change scenarios derived in this study were broadly in line with other studies, with the majority of scenar- ios indicating wetter conditions in the future. Translating the impacts in to runoff in the basin showed increased future mean flows, although these would be offset to some degree by rising evapotranspiration. I mpacts on extreme runoff indi- cated the possibility of more severe fl oods in future. These are likely to be exacerbated by land-use changes including overgrazing, deforestation, and improper farming practices. Blue Nile basin flood managers the refore need to continue to prepare for the possibility of more frequent floods by adopting a range of measures to mi nimise loss of life and guard against other flood damage.","PeriodicalId":247243,"journal":{"name":"The Open Hydrology Journal","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127014471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-12-30DOI: 10.2174/1874378101004010211
N. Sharma, F. Johnson, C. Hutton, M. Clark
The authors present an assessment of risk from river bank erosion in the Brahmaputra river basin. The concept of risk is conceptualised in the context of socio-economic vulnerability, and the potential for exposure to hazard. By addressing both the physical hazard and the variations across the socio-economic surface the approach presented attempts to spatially combine these parameters to provide a risk surface for use by policy makers and decision makers at a number of administrative levels. The concept of vulnerability and risk as a description of the status of a society with respect to an imposed hazard such as flooding or the associated bank erosion exacerbated by climate change is deep rooted in a very broad research effort and its associated publications. In part, this reflects the complex evolution of the underlying notion of hazard - which itself shows the concurrent evolution of a series of strands each representing one disciplinary tradition. The concept of vulnerability has been very widely treated in the literature, and For present purposes an acceptable approach to vulnerability may be to start with an influential (but still controversial) established model by IPCC (2001) who have developed working definition - and then explore its ramifications in order to develop a set of working definitions and operational indicators for the project. This provides a pragmatic route towards a realistic target. It also offers a possible buffer against the common experience that the more sophisticated indices of vulnerability are strongly sensitive to contingent local/historical circumstances. This approach is explored within this chapter. The hazard posed by unabated bank erosion has been analysed with the help of satellite imagery based data and through adoption of Plan Form Index along with its threshold values develop for the Brahmaputra. The land loss to erosion is depicting a significantly rising trend which has obviously contributed to the impoverishment of the riverine population. The attendant uncertainties of climate change of hydrological and hydraulic river behaviour may exacerbate the channel instability of the Brahmaputra.
作者对雅鲁藏布江流域的河岸侵蚀风险进行了评估。风险的概念是在社会经济脆弱性和暴露于危险的可能性的背景下概念化的。通过处理物理危害和社会经济层面的变化，提出的方法试图在空间上将这些参数结合起来，以提供一个风险层面，供若干行政层面的决策者和决策者使用。脆弱性和风险的概念是对一个社会在洪水或因气候变化而加剧的相关河岸侵蚀等强加危害方面的状况的描述，这一概念深深植根于广泛的研究工作及其相关出版物中。在某种程度上，这反映了潜在危险概念的复杂演变——它本身显示了代表一个学科传统的一系列分支的并行演变。脆弱性的概念在文献中已经得到了非常广泛的处理，就目前而言，一个可接受的脆弱性方法可能是从IPCC(2001)建立的一个有影响力(但仍有争议)的模型开始，该模型已经制定了工作定义，然后探索其后果，以便为该项目制定一套工作定义和操作指标。这为实现一个现实的目标提供了一条务实的途径。它还提供了一种可能的缓冲，以防止更复杂的脆弱性指数对偶然的地方/历史情况非常敏感的共同经验。本章将探讨这种方法。在卫星图像数据的帮助下，通过采用Plan Form Index及其为雅鲁藏布江开发的阈值，对有增无减的河岸侵蚀造成的危害进行了分析。水土流失呈明显上升趋势，这是造成流域人口贫困化的主要原因。随之而来的气候变化对河流水文和水力行为的不确定性可能加剧雅鲁藏布江的河道不稳定。
{"title":"Hazard, vulnerability and risk on the Brahmaputra basin: a case study of river bank erosion.","authors":"N. Sharma, F. Johnson, C. Hutton, M. Clark","doi":"10.2174/1874378101004010211","DOIUrl":"https://doi.org/10.2174/1874378101004010211","url":null,"abstract":"The authors present an assessment of risk from river bank erosion in the Brahmaputra river basin. The concept of risk is conceptualised in the context of socio-economic vulnerability, and the potential for exposure to hazard. By addressing both the physical hazard and the variations across the socio-economic surface the approach presented attempts to spatially combine these parameters to provide a risk surface for use by policy makers and decision makers at a number of administrative levels. The concept of vulnerability and risk as a description of the status of a society with respect to an imposed hazard such as flooding or the associated bank erosion exacerbated by climate change is deep rooted in a very broad research effort and its associated publications. In part, this reflects the complex evolution of the underlying notion of hazard - which itself shows the concurrent evolution of a series of strands each representing one disciplinary tradition. The concept of vulnerability has been very widely treated in the literature, and For present purposes an acceptable approach to vulnerability may be to start with an influential (but still controversial) established model by IPCC (2001) who have developed working definition - and then explore its ramifications in order to develop a set of working definitions and operational indicators for the project. This provides a pragmatic route towards a realistic target. It also offers a possible buffer against the common experience that the more sophisticated indices of vulnerability are strongly sensitive to contingent local/historical circumstances. This approach is explored within this chapter. The hazard posed by unabated bank erosion has been analysed with the help of satellite imagery based data and through adoption of Plan Form Index along with its threshold values develop for the Brahmaputra. The land loss to erosion is depicting a significantly rising trend which has obviously contributed to the impoverishment of the riverine population. The attendant uncertainties of climate change of hydrological and hydraulic river behaviour may exacerbate the channel instability of the Brahmaputra.","PeriodicalId":247243,"journal":{"name":"The Open Hydrology Journal","volume":"110 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124823424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-12-30DOI: 10.2174/1874378101004010113
A. Adeloye, C. Ojha
Lake Malawi was the subject of the work by Kumanbala and Ervine. The lake is the most strategic in Malawi by serving various purposes including hydropower generation, water supply for industrial and domestic use in the city of Blantyre and its surrounding urban areas, together with irrigation water in the Lower Shire Valley (LSV). Consequently, any changes in the hydrological or ecological behaviour of the lake will have far reaching consequences for the economy of Malawi. It is therefore no wonder that the lake has been intensively studied in the past but the main contribution of the current authors was to incorporate climate change modelling into the existing water balance model, so as to enable objective and more comprehensive assessment of the likely future behaviour of the lake. The results showed that water level in the lake will continue to drop because of decreasing rainfall and increasing evaporation. This situation calls for an urgent need to develop viable alternatives for both hydropower and irrigation development, since the current over-reliance on the lake’s water may not be sustainable for the future.
{"title":"Editorial- Analysis of Climate Change Impacts on Water Resources For Developing Economies: Successes and Challenges","authors":"A. Adeloye, C. Ojha","doi":"10.2174/1874378101004010113","DOIUrl":"https://doi.org/10.2174/1874378101004010113","url":null,"abstract":"Lake Malawi was the subject of the work by Kumanbala and Ervine. The lake is the most strategic in Malawi by serving various purposes including hydropower generation, water supply for industrial and domestic use in the city of Blantyre and its surrounding urban areas, together with irrigation water in the Lower Shire Valley (LSV). Consequently, any changes in the hydrological or ecological behaviour of the lake will have far reaching consequences for the economy of Malawi. It is therefore no wonder that the lake has been intensively studied in the past but the main contribution of the current authors was to incorporate climate change modelling into the existing water balance model, so as to enable objective and more comprehensive assessment of the likely future behaviour of the lake. The results showed that water level in the lake will continue to drop because of decreasing rainfall and increasing evaporation. This situation calls for an urgent need to develop viable alternatives for both hydropower and irrigation development, since the current over-reliance on the lake’s water may not be sustainable for the future.","PeriodicalId":247243,"journal":{"name":"The Open Hydrology Journal","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117178320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-12-30DOI: 10.2174/1874378101004010163
L. Oyebande, S. Odunuga
The series of droughts of the past three decades that affected the Sudano-Sahelian zone of West Africa, particu- larly Niger, Volta and Senegal basins impacted the water resources, ecosystems and the fragile economies of at least 13 of the 16 countries of the region. Declining rainfall, highly variable in time and space has resulted in more than proportionate decrease in river discharges, and declining level of freshwater bodies. This situation translated into falling groundwater levels and accelerated desertification process, hence major crises of food insecurity and massive migration, which often leads to conflicts. The challenges and uncertainties associated with the impacts of future climate changes on water re- sources in West Africa are further compounded by many other factors, including regional demographic factors, non- existing or inadequate water policies, inefficient management strategies and lack of reliable and adequate data. This paper synthesizes the state of art research regarding climate change impact on water resources in West Africa economies of Senegal, Niger and Volta Basins while also making prescriptions on what can be done in terms of adaptation strategies, rather than mitigation, to reduce the severity of the expected impacts on the already stressed and poverty-stricken econo- mies of West Africa,
{"title":"Climate change impact on water resources at the transboundary level in West Africa: the cases of the Senegal, Niger and Volta basins.","authors":"L. Oyebande, S. Odunuga","doi":"10.2174/1874378101004010163","DOIUrl":"https://doi.org/10.2174/1874378101004010163","url":null,"abstract":"The series of droughts of the past three decades that affected the Sudano-Sahelian zone of West Africa, particu- larly Niger, Volta and Senegal basins impacted the water resources, ecosystems and the fragile economies of at least 13 of the 16 countries of the region. Declining rainfall, highly variable in time and space has resulted in more than proportionate decrease in river discharges, and declining level of freshwater bodies. This situation translated into falling groundwater levels and accelerated desertification process, hence major crises of food insecurity and massive migration, which often leads to conflicts. The challenges and uncertainties associated with the impacts of future climate changes on water re- sources in West Africa are further compounded by many other factors, including regional demographic factors, non- existing or inadequate water policies, inefficient management strategies and lack of reliable and adequate data. This paper synthesizes the state of art research regarding climate change impact on water resources in West Africa economies of Senegal, Niger and Volta Basins while also making prescriptions on what can be done in terms of adaptation strategies, rather than mitigation, to reduce the severity of the expected impacts on the already stressed and poverty-stricken econo- mies of West Africa,","PeriodicalId":247243,"journal":{"name":"The Open Hydrology Journal","volume":"247 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126158596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-12-30DOI: 10.2174/1874378101004010115
Subimal Ghosh, Chaitali Misra
Climate Change refers to any systematic change in the long-term statistics of climate elements (such as tem- perature, pressure, or winds) sustained over several decades or longer time periods. General Circulation Models (GCMs) are tools designed to simulate time series of climate variables globally, accounting for effects of greenhouse gases in the atmosphere and resulting global climate change. They are currently the most credible tools available for simulating the re- sponse of the global climate system to increasing greenhouse gas concentrations, and to provide estimates of climate vari- ables (e.g. air temperature, precipitation, wind speed, pressure etc.) on a global scale. GCMs demonstrate a significant skill at the continental and hemispheric spatial scales and incorporate a large proportion of the complexity of the global system; they are, however, inherently unable to represent local subgrid-scale features and dynamics. The spatial scale on which a GCM can operate (e.g., 3.75 0 longitude X 3.75 0 latitude for Coupled Global Climate Model, CGCM2) is very coarse compared to that of a hydrologic process (e.g., precipitation in a region, streamflow in a river etc.) of interest in the climate change impact assessment studies. Moreover, accuracy of GCMs, in general, decreases from climate related vari- ables, such as wind, temperature, humidity and air pressure to hydrologic variables such as precipitation, evapotranspira- tion, runoff and soil moisture, which are also simulated by GCMs. These limitations of the GCMs restrict the direct use of their output in hydrology. Hydrologic implications of global climate change are usually assessed by downscaling appro- priate predictors simulated by General Circulation Models (GCMs). Conventionally rainfall is first downscaled with dy- namic or statistical downscaling and then the predicted rainfall is used in hydrologic models to forecast hydrologic scenar- ios of future. Although this methodology is widely practiced, there are some limitations: (a) uncertainty resulting from the use of multi- ple GCMs, scenarios, downscaling models is seldom considered; (b) local changes (e.g., urbanization, population growth, deforestation) which affect directly the hydrology of a region are considered in a very limited number of studies. The pre- sent paper focuses on these limitations and proposes different approaches to deal with the problems.
{"title":"Assessing Hydrological Impacts of Climate Change: Modeling Techniques and Challenges","authors":"Subimal Ghosh, Chaitali Misra","doi":"10.2174/1874378101004010115","DOIUrl":"https://doi.org/10.2174/1874378101004010115","url":null,"abstract":"Climate Change refers to any systematic change in the long-term statistics of climate elements (such as tem- perature, pressure, or winds) sustained over several decades or longer time periods. General Circulation Models (GCMs) are tools designed to simulate time series of climate variables globally, accounting for effects of greenhouse gases in the atmosphere and resulting global climate change. They are currently the most credible tools available for simulating the re- sponse of the global climate system to increasing greenhouse gas concentrations, and to provide estimates of climate vari- ables (e.g. air temperature, precipitation, wind speed, pressure etc.) on a global scale. GCMs demonstrate a significant skill at the continental and hemispheric spatial scales and incorporate a large proportion of the complexity of the global system; they are, however, inherently unable to represent local subgrid-scale features and dynamics. The spatial scale on which a GCM can operate (e.g., 3.75 0 longitude X 3.75 0 latitude for Coupled Global Climate Model, CGCM2) is very coarse compared to that of a hydrologic process (e.g., precipitation in a region, streamflow in a river etc.) of interest in the climate change impact assessment studies. Moreover, accuracy of GCMs, in general, decreases from climate related vari- ables, such as wind, temperature, humidity and air pressure to hydrologic variables such as precipitation, evapotranspira- tion, runoff and soil moisture, which are also simulated by GCMs. These limitations of the GCMs restrict the direct use of their output in hydrology. Hydrologic implications of global climate change are usually assessed by downscaling appro- priate predictors simulated by General Circulation Models (GCMs). Conventionally rainfall is first downscaled with dy- namic or statistical downscaling and then the predicted rainfall is used in hydrologic models to forecast hydrologic scenar- ios of future. Although this methodology is widely practiced, there are some limitations: (a) uncertainty resulting from the use of multi- ple GCMs, scenarios, downscaling models is seldom considered; (b) local changes (e.g., urbanization, population growth, deforestation) which affect directly the hydrology of a region are considered in a very limited number of studies. The pre- sent paper focuses on these limitations and proposes different approaches to deal with the problems.","PeriodicalId":247243,"journal":{"name":"The Open Hydrology Journal","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129305370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2010-12-30DOI: 10.2174/1874378101004010152
P. Kumambala, A. Ervine
Sustainable water resources development of Malawi needs a thorough assessment of the impact of climate change on the future water levels of Lake Malawi because Lake Malawi together with its outflowing Shire river water sys- tem is Malawi's most important water resource for hydropower generation, water supply for industrial and domestic use in the city of Blantyre and its surrounding urban areas together with irrigation water in the Lower Shire Valley (LSV). Any changes in the hydrological or ecological behaviour of the lake will have far reaching consequences on the economy of Malawi. This paper reviews the current literature on the water balance studies of Lake Malawi and introduces climate change modelling into the water balance model to assess the likely future behaviour of the lake.
马拉维的可持续水资源开发需要对气候变化对马拉维湖未来水位的影响进行彻底的评估，因为马拉维湖及其流出的Shire河水系是马拉维最重要的水资源，用于水力发电、为Blantyre市及其周边城市地区的工业和家庭供水，以及下Shire Valley (LSV)的灌溉用水。湖泊水文或生态行为的任何变化都将对马拉维的经济产生深远的影响。本文综述了马拉维湖水平衡研究的现有文献，并将气候变化模型引入到水平衡模型中，以评估该湖未来可能的行为。
{"title":"Water Balance Model of Lake Malawi and its Sensitivity to Climate Change","authors":"P. Kumambala, A. Ervine","doi":"10.2174/1874378101004010152","DOIUrl":"https://doi.org/10.2174/1874378101004010152","url":null,"abstract":"Sustainable water resources development of Malawi needs a thorough assessment of the impact of climate change on the future water levels of Lake Malawi because Lake Malawi together with its outflowing Shire river water sys- tem is Malawi's most important water resource for hydropower generation, water supply for industrial and domestic use in the city of Blantyre and its surrounding urban areas together with irrigation water in the Lower Shire Valley (LSV). Any changes in the hydrological or ecological behaviour of the lake will have far reaching consequences on the economy of Malawi. This paper reviews the current literature on the water balance studies of Lake Malawi and introduces climate change modelling into the water balance model to assess the likely future behaviour of the lake.","PeriodicalId":247243,"journal":{"name":"The Open Hydrology Journal","volume":"2673 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125012967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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