Pub Date : 2015-12-15DOI: 10.1080/23312041.2015.1115691
G. Dwarakish, B. P. Ganasri
Abstract Hydrologic modeling plays a very important role in assessing the seasonal water availability, which is necessary to take decisions in water resources management. Both climate and land use and land cover change have great influence on the hydrological response of a watershed. The main aim of this study is to provide a detailed review of studies which have been carried out to analyze the hydrological impacts of land use change, and also to evaluate different scenario modeling approaches. In addition, a brief description of basic hydrologic models which are used to simulate the stream flow is provided. This review paper tried to explain the importance of model comparison and performance evaluation in modeling studies. The following conclusions may be drawn from this review: (1) it is necessary to model the possible impacts of land use change and climate change in order to proceed with effective water resources management, (2) it is important to analyze the variation in hydrological response in catchments with different land use characteristics and climatic conditions and also under climate scenarios, and (3) integration of different models with hydrologic models can be considered as an efficient method to forecast future trends in hydrological response.
{"title":"Impact of land use change on hydrological systems: A review of current modeling approaches","authors":"G. Dwarakish, B. P. Ganasri","doi":"10.1080/23312041.2015.1115691","DOIUrl":"https://doi.org/10.1080/23312041.2015.1115691","url":null,"abstract":"Abstract Hydrologic modeling plays a very important role in assessing the seasonal water availability, which is necessary to take decisions in water resources management. Both climate and land use and land cover change have great influence on the hydrological response of a watershed. The main aim of this study is to provide a detailed review of studies which have been carried out to analyze the hydrological impacts of land use change, and also to evaluate different scenario modeling approaches. In addition, a brief description of basic hydrologic models which are used to simulate the stream flow is provided. This review paper tried to explain the importance of model comparison and performance evaluation in modeling studies. The following conclusions may be drawn from this review: (1) it is necessary to model the possible impacts of land use change and climate change in order to proceed with effective water resources management, (2) it is important to analyze the variation in hydrological response in catchments with different land use characteristics and climatic conditions and also under climate scenarios, and (3) integration of different models with hydrologic models can be considered as an efficient method to forecast future trends in hydrological response.","PeriodicalId":42883,"journal":{"name":"Cogent Geoscience","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2015-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23312041.2015.1115691","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60091482","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 : 2015-12-15DOI: 10.1080/23312041.2015.1117829
Churchill Okonkwo, B. Demoz, R. Sakai, C. Ichoku, C. Anarado, J. Adegoke, A. Amadou, S. I. Abdullahi
Abstract In this study, the combined effect of the Atlantic Multidecadal Oscillation (AMO) and El Niño Southern Oscillation (ENSO) on the Lake Chad (LC) level variability is explored. Our results show that the lake level at the Bol monitoring station has a statistically significant correlation with precipitation (R2 = 0.6, at the 99.5% confidence level). The period between the late 1960s and early 1970s marked a turning point in the response of the regional rainfall to climatic drivers, thereby severely affecting the LC level. Our results also suggest that the negative impact of the cold phase of AMO on Sahel precipitation masks and supersedes the positive effect of La Niña in the early the 1970s. The drop in the size of LC level from 282.5 m in the early 1960s to about 278.1 m in 1983/1984 was the largest to occur within the period of study (1900–2010) and coincides with the combined cold phase of AMO and strong El Niño phase of ENSO. Further analyses show that the current warm phase of AMO and increasing La Niña episodes appear to be playing a major role in the increased precipitation in the Sahel region. The LC level is responding to this increase in precipitation by a gradual recovery, though it is still below the levels of the 1960s. This understanding of the AMO–ENSO–rainfall–LC level association will help in forecasting the impacts of similar combined episodes in the future. These findings also have implications for long-term water resources management in the LC region.
{"title":"Combined effect of El Niño southern oscillation and Atlantic multidecadal oscillation on Lake Chad level variability","authors":"Churchill Okonkwo, B. Demoz, R. Sakai, C. Ichoku, C. Anarado, J. Adegoke, A. Amadou, S. I. Abdullahi","doi":"10.1080/23312041.2015.1117829","DOIUrl":"https://doi.org/10.1080/23312041.2015.1117829","url":null,"abstract":"Abstract In this study, the combined effect of the Atlantic Multidecadal Oscillation (AMO) and El Niño Southern Oscillation (ENSO) on the Lake Chad (LC) level variability is explored. Our results show that the lake level at the Bol monitoring station has a statistically significant correlation with precipitation (R2 = 0.6, at the 99.5% confidence level). The period between the late 1960s and early 1970s marked a turning point in the response of the regional rainfall to climatic drivers, thereby severely affecting the LC level. Our results also suggest that the negative impact of the cold phase of AMO on Sahel precipitation masks and supersedes the positive effect of La Niña in the early the 1970s. The drop in the size of LC level from 282.5 m in the early 1960s to about 278.1 m in 1983/1984 was the largest to occur within the period of study (1900–2010) and coincides with the combined cold phase of AMO and strong El Niño phase of ENSO. Further analyses show that the current warm phase of AMO and increasing La Niña episodes appear to be playing a major role in the increased precipitation in the Sahel region. The LC level is responding to this increase in precipitation by a gradual recovery, though it is still below the levels of the 1960s. This understanding of the AMO–ENSO–rainfall–LC level association will help in forecasting the impacts of similar combined episodes in the future. These findings also have implications for long-term water resources management in the LC region.","PeriodicalId":42883,"journal":{"name":"Cogent Geoscience","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2015-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23312041.2015.1117829","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60091497","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 : 2015-10-08DOI: 10.1080/23312041.2015.1084669
K. Das, P. K. Paul
Abstract The spatiotemporal distribution of soil moisture is a key variable for hydrological and meteorological applications that influences the exchange of water and energy fluxes at the land surface/atmosphere interface. Accurate estimate of the spatiotemporal variations of soil moisture is critical for numerous large-scale environmental studies. Recent technological advances in satellite remote sensing have shown that soil moisture can be measured by a variety of remote sensing techniques, each with its own strengths and weaknesses which minimizes the ill-posed conventional problems. Technical and methodological advances such as multi-configuration radar and forthcoming SAR constellations are increasingly mitigating the shortcomings of SAR with respect to soil moisture estimation at the field and catchment scale. This paper presents a comprehensive review of few selected inversion methods of soil moisture, with focus on technique in passive microwave and active microwave measurements, in addition to the factors which affect the microwave return. The theoretical and physical principles and the status of current basic retrieval methods are summarized. Limitations existing in current soil moisture estimation algorithms and the major influencing factors including radar configurations (polarization, incidence angel and frequency of bands) and soil surface characteristics on backscattering coefficient have been addressed and also discussed.
{"title":"Present status of soil moisture estimation by microwave remote sensing","authors":"K. Das, P. K. Paul","doi":"10.1080/23312041.2015.1084669","DOIUrl":"https://doi.org/10.1080/23312041.2015.1084669","url":null,"abstract":"Abstract The spatiotemporal distribution of soil moisture is a key variable for hydrological and meteorological applications that influences the exchange of water and energy fluxes at the land surface/atmosphere interface. Accurate estimate of the spatiotemporal variations of soil moisture is critical for numerous large-scale environmental studies. Recent technological advances in satellite remote sensing have shown that soil moisture can be measured by a variety of remote sensing techniques, each with its own strengths and weaknesses which minimizes the ill-posed conventional problems. Technical and methodological advances such as multi-configuration radar and forthcoming SAR constellations are increasingly mitigating the shortcomings of SAR with respect to soil moisture estimation at the field and catchment scale. This paper presents a comprehensive review of few selected inversion methods of soil moisture, with focus on technique in passive microwave and active microwave measurements, in addition to the factors which affect the microwave return. The theoretical and physical principles and the status of current basic retrieval methods are summarized. Limitations existing in current soil moisture estimation algorithms and the major influencing factors including radar configurations (polarization, incidence angel and frequency of bands) and soil surface characteristics on backscattering coefficient have been addressed and also discussed.","PeriodicalId":42883,"journal":{"name":"Cogent Geoscience","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2015-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23312041.2015.1084669","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60091900","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 : 2015-10-02DOI: 10.1080/23312041.2015.1085296
Geeta Singh, Dinesh Kumar, P. Sharma
Abstract The aim of this study was to investigate the response of soil microbial parameters to nutrient management practices involving organic amendments, farmyard manure (FYM), vermicompost (VC), crop residues (CR) and biofertilizers (BF) in rice–wheat and rice–wheat–mung bean cropping system of the Indo-Gangetic Plains, India. Soil microbial biomass C (Cmic), basal respiration, ergosterol, glomalin, soil enzymes (glucosidases, phosphatases and dehydrogenases), FDA activity, organic carbon (Corg), Cmic-to-Corg ratio and metabolic quotient (qCO2) were estimated in soil samples collected at 0–15 cm depth. The highest Corg (0.64%) and Cmic (103.8 μg g−1) soil levels occurred in the treatment receiving a combination of VC, CR and BF. Soil respiration, Corg and Cmic-to-Corg ratio were significantly enhanced by the input of CR to plots receiving FYM and VC. The qCO2 was the highest in plots receiving a combination of FYM, CR and BF followed by control (no nutrient input) and least in plots receiving a combination of VC, crop residue and biofertilizer. These results indicate that the organic practices involving VC, CR and BF improved soil microbial characteristics and Corg in rice–wheat systems.
{"title":"Effect of organics, biofertilizers and crop residue application on soil microbial activity in rice – wheat and rice-wheat mungbean cropping systems in the Indo-Gangetic plains","authors":"Geeta Singh, Dinesh Kumar, P. Sharma","doi":"10.1080/23312041.2015.1085296","DOIUrl":"https://doi.org/10.1080/23312041.2015.1085296","url":null,"abstract":"Abstract The aim of this study was to investigate the response of soil microbial parameters to nutrient management practices involving organic amendments, farmyard manure (FYM), vermicompost (VC), crop residues (CR) and biofertilizers (BF) in rice–wheat and rice–wheat–mung bean cropping system of the Indo-Gangetic Plains, India. Soil microbial biomass C (Cmic), basal respiration, ergosterol, glomalin, soil enzymes (glucosidases, phosphatases and dehydrogenases), FDA activity, organic carbon (Corg), Cmic-to-Corg ratio and metabolic quotient (qCO2) were estimated in soil samples collected at 0–15 cm depth. The highest Corg (0.64%) and Cmic (103.8 μg g−1) soil levels occurred in the treatment receiving a combination of VC, CR and BF. Soil respiration, Corg and Cmic-to-Corg ratio were significantly enhanced by the input of CR to plots receiving FYM and VC. The qCO2 was the highest in plots receiving a combination of FYM, CR and BF followed by control (no nutrient input) and least in plots receiving a combination of VC, crop residue and biofertilizer. These results indicate that the organic practices involving VC, CR and BF improved soil microbial characteristics and Corg in rice–wheat systems.","PeriodicalId":42883,"journal":{"name":"Cogent Geoscience","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2015-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/23312041.2015.1085296","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60091909","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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