Ecohydrology & Hydrobiology最新文献

Freshwater phytoplankton blooms are increasing in frequency worldwide and regularly put potable water resources, critical to human welfare, in jeopardy. Much more information is needed to effectively predict and mitigate these blooms. Prior studies have highlighted the roles played by both biological factors and physical ones (e.g., hydrodynamics, temperature, precipitation) in bloom formation. Most comprehensive studies have been limited to the temperate zone in Europe, China or North America; the dynamics of tropical and sub-tropical reservoirs are less well-characterised. Numerous studies have highlighted the relationship between phytoplankton and temperature or precipitation, but few have focused on the temporal scale of these relationships. This work evaluates the water quality of 155 freshwater reservoirs in Ceara state in northeast Brazil. We propose weather and climate conditions as natural drivers for changes in chlorophyll-a, cyanobacteria, total phosphorus and total nitrogen concentrations, that we consider as water quality parameters. We hypothesise that links between water quality and temperature and precipitation strongly depend on the timescale considered. Additionally, we propose a statistical definition, based on percentile thresholds, of extremes events in water quality, a criterion that has been lacking for the study of freshwater algal blooms and that will enable new regional and global comparisons. We aim to explore the potential links between extremes in water quality in tropical freshwater bodies of Ceara their predictors, by applying a multitemporal scale approach and discriminating the impact of the daily weather fluctuations from interannual climate variability. We find that water quality in Ceara is frequently below international standards, representing a threat for human and animal welfare. Reservoirs’ water level was  a key predictor of bloom occurrence, thus linking low annual accumulated precipitation to inferior water quality. At the daily scale, high temperature promotes bloom formation during periods of drought. These findings suggest enhanced precautions during dry periods when the reservoirs are most prone to algal blooms, which can aggravate the drinking water scarcity in these years.

The hydrologic regulation analysis on a basin scale requires the understanding of the spatio-temporal heterogeneity of the climate regime and the land cover. The Cusiana river sub-basin (4992 km²) is part of the Colombian Orinoco River basin and its important because of the ecosystem services it provides. However, there is limited knowledge about the factors that govern its hydrological functioning. In this study we aimed at describing the relation between the forest cover and the hydroclimatic tendencies with the hydrologic regulation of this basin. For this, we evaluated rainfall and evapotranspiration spatial variability and the temporal tendencies of these variables and streamflow employing the Mann-Kendall test for a dataset covering from 1980 till 2020. Streamflow data was obtained from various gauging sites at different points along the main streambed between 290 and 3135 m a.s.l. We also evaluated the basin's forest cover changes between 2003 and 2019 using official land cover classification maps. With the hydroclimatic and land cover analyzes we created potential scenarios of extreme dry and wet years and of deforestation and restoration. These extreme scenarios were forced in the previously calibrated and validated Seasonal Water Yield module of the InVEST model to evaluate their effects on base and quickflows. Results show that there are no homogeneous tendencies in the rainfall, evapotranspiration, or streamflow within this basin. Furthermore, streamflow tends to decrease in the basin segments that show an increase in forest cover. The model outputs suggest that the magnitude of the baseflow decrease under a deforestation scenario is up to 3.6 times larger than the increase in baseflow under a forest cover restoration scenario, and that the quickflows can increase up to 1.4 times more in a combined wet year and deforestation scenario, than in an average year under current forest cover. From our results we identify that the spatial relation between land cover, climate and hydrologic regulation must be explicitly evaluated for the design of water resources management plans for any Andean River basin.

Water budget components of endorheic basins of semi-arid and karstic characters are difficult to assess. In this study, we attempt to estimate the water budget components of the Konya Endorheic Basin (KEB), which is a semi-arid, karstic basin in central Anatolia, using The Gravity Recovery and Climate Experiment mission (GRACE) observations and Global Land Data Assimilation System (GLDAS) data over the period 2002-2019. We also investigate the trends and sub-trends in the time series of the hydrometeorological parameters. The results indicate that the available water potential in the basin has a decreasing trend over the study period. Precipitation and evapotranspiration show increasing trends in the basin, however, the other hydrometeorological parameters demonstrate decreasing trends. Both Terrestrial Water Storage Anomaly (TWSA) and groundwater level decrease significantly (20.21 mm/yr and 122.34 mm/yr, respectively). The dry 2008 and subsequent wet year created a hydrological breaking point in the time series. The weights of soil moisture and groundwater storages are relatively large amongst the TWSA components (49.61% and 33.12%, respectively). The surface water storage anomaly comes at the third place with a 14% weight. It is assessed that the groundwater storage system responds to precipitation with a delay of 6 months. Limestone zones respond more sharply to groundwater depletion than alluvial zones. It should be noted that the GRACE and GLDAS data could be used together to successfully estimate the water budget components for sustainable management of the limited water resources of the basin.

Abstract: Fog interception is a significant component of the water balance of Southern Appalachian spruce-fir forests in the Southeast USA. Here, fog interception rates are quantified for spruce-fir and northern hardwood trees in Great Smoky Mountains National Park (GSMNP), Tennessee and North Carolina, as a precursor to examining how interspecific differences in fog interception could affect catchment water balances if there is widespread vegetation change from spruce-fir to hardwoods. A water-balance approach was implemented, based on paired open-site (rainfall) and beneath-canopy (throughfall) electronically recording tipping-bucket rain gauges that were in place in the spruce-fir zone of GSMNP from May to November 2021. Comparing identified fog interception events to actual conditions captured by a webcam, 90% of verifiable events had conditions that were either clearly or potentially favorable for fog interception. Estimated fog interception gain ranged from averages of 0.24 to 0.69 mm day⁻¹, representing 3 to 8% of rainfall. Results are consistent with the expectation of higher fog interception gain for spruce and fir than for birch, the representative hardwood species. Quantification of fog interception rates provides valuable information about ecohydrological processes in ecologically significant Southern Appalachian spruce-fir forests.

Following the declaration of the UN Decade on Ecosystem Restoration, nature-based solutions (NbS) are at the forefront of the sustainability discourse. However, this solution needs operational clarity to avoid the commonly mentioned vagueness of the concept. This paper highlighted application of the ecohydrological principles to guide the conception, planning, designing, implementation, and monitoring of nature-based solutions. The paper proposed an ecohydrological nature-based solution that is emanated from the natural sequence of self-regulating patch-interpatch at the hillslope scale to restore highly degraded hillslope in Lake Hawassa sub-basin of Ethiopian Rift Valley Basin. The active restoration site is found to have a landscape organization index value of 0.94 (= 94% of the gradsect is consisting of resources conserving patches) as compared to 0.16 at the passive site. In terms of landscape functionality, the active site showed significant stability (p(x≤T) = 0.01), infiltration (p(x≤T) = 0.001), and nutrient cycling (p(x≤T)=0.005). It also exhibited significant improvement in soil moisture (p(x≤T) = 0.001). Ecologically, the active site is found to be more diverse (richness index 18 (active) vs. 8 (passive); heterogeneous (Shannon diversity index=1.22 (active) vs. 0.44 (passive)); well distributed (Simpson's index= 0.62 (active) vs. 0.28 (passive)); less dominance of few species (Evenness index (0.99 (passive) vs. 0.96 (active)). Limitation of this study is linked with the short span of the restoration period which tends to be not adequate to observe the full ‘dual’ regulation between hydrology and biota. For this, the research can be considered as a prerequisite towards full restoration of the landscape.

Jakarta City is one of the largest cities in Indonesia, experiencing urban areas development generally intensive and unsustainable. This development impacts directly or indirectly on landscape degradation. Kalijodo is one of the important public open spaces (POS) constructed in the Jakarta Capital Special Region to facilitate different social functions and ecosystem services. This paper aims to describe the non-ideal condition of the Kalijodo area as a POS and to strengthen its functions towards a Public Green Open Space (PGOS). The Kalijodo POS had actually 47.91 % vegetated and 52.09 % of non-vegetated land cover and this area cannot be categorized as PGOS due to its vegetated land cover under a minimum threshold of 75 %. This condition is closely related to other aspects and parameters which indicate that Kalijodo POS has low water absorption ability, low water storage capacity, high average air temperature, high Thermal Humidity Index (THI), and low potential for economic benefits. The ecohydrology principles were taken into consideration for understanding, assessment, and identification of possible efforts to achieve the PGOS level. Several possible actions would be suggested for improvement consisting of increasing vegetated land cover, replacing pavement hardeners, introducing bio pores, constructing water ponds and wetlands, increasing public participation, and adjusting appropriate government policy and regulations. These efforts will probably have positive impacts on average air temperature reduction, increasing water absorption ability and potential economic gain, entering THI to a comfort zone and positive people's perception, as well as increasing people attendance.

This study quantified the total evapotranspiration (ET) flux of three major types of macrophytes that cover lacustrine fringe wetlands in Lake Tana, Ethiopia during the dry season, April and May, 2022. This study was conducted to understand lacustrine wetland macrophytes' ET rates and provide an important guideline for designing their conservation and restoration plans. To assess ET rates during the peak dry season, three macrophytes of lacustrine wetlands in Lake Tana were chosen: Eichhornia crassipes (water hyacinth), Cyperus papyrus, and Echinochloa stagnina. Three replicate lysimeters for each of the three treatment types (macrophytes) and one control type (open water) were applied to measure ET. To calculate reference evapotranspiration (ET_o), FAO's ET_o Calculator Version 3.2 was applied. All statistical analyses were carried out using R software. The results of ET rates from wetland macrophytes (9.05mm/day) were considered to be significantly higher than open water evaporation (5.90mm/day). There was a significant difference in mean ET among the macrophytes [F (3, 488) = 194.6, p < 2e-16 ***]. In this study, crop coefficient (K_c1) (1.99 ± 0.65) referenced to FAO Penman–Monteith ET_o is greater than K_c2 (1.58 ± 0.59) referenced to open water evaporation (E_ow). In terms of wetland macrophyte type, E. crassipes had the maximum mean Kc values (K_c1 = 2.51±0.70 and K_c2 = 2.02±0.67). E. stagnina had the minimum mean Kc values (K_c1 = 1.52±0.32 and K_c2 = 1.19±0.24). Except for open water which strongly correlated with sunshine hours (r = 0.61) and solar radiation (r = 0.60), the correlation among daily ET values and meteorological variables was found to be weak. The result of our research indicated that the presence of floating macrophytes of E. crassipes will increase the ET flux during the dry season more than emergent macrophytes and open water surfaces. Our findings could provide an important guideline for designing conservation and restoration plans for C. papyrus and E. stagnina to reverse the spread of E. crassipes and maintaining lacustrine fringe wetlands for fish breeding ground and sediment control.

This work addresses the challenge of classifying watersheds to support land use policy-making in rapidly developing, wet tropical regions, using a case study of the Brantas River Basin, Java, Indonesia. Hierarchical Clustering on Principal Components of the watershed descriptors resulted in three optimal clusters. Differentiation among these three clusters is mainly related to climatic regimes, topographic features, and land uses. Stepwise regression was used to identify the watershed descriptors that explain the spatial variability of four flow indices (95% non-exceedance percentile Q95; 5% non-exceedance percentile Q5; the slope of the flow duration curve SFDC; and the runoff coefficient RC). This gave, for these four indices in turn, R² values of 0.77, 0.76, 0.84 and 0.45. The results show that built-up areas and dryland forest are primary land-use controls on flow indices. Clustering results suggest that existing regional development trends will have major hydrological impacts, especially related to runoff generation and groundwater. The results support the view that failure to implement land-use policy – failure that is expected to increase built-up areas across the watershed and increase forest loss in the upper watershed - will jeopardize watershed hydrological functions. The findings of this research support the need for frequent and updated land-use monitoring to control urban development and conserve dryland forest, as well as land-use policies that control increases in built-up areas and that minimize forest loss.

In Mongolia, overuse and degradation of groundwater is a serious issue. The authors have recently applied a process-based eco-hydrology model, NICE (National Integrated Catchment-based Eco-hydrology) to urban and mining hubs to explicitly quantify spatio-temporal variations in water availability. In this study, NICE was scaled up to the total of 29 river basins in the entire country. The model simulated the effect of past climatic change and human activity on water resources during 1980-2018 there. The model reasonably reproduced observed river discharge with a maximal value during summer rainfall seasons. The simulation also revealed heterogeneous distributions of hydrologic budget and its response to climatic and anthropogenic disturbances. In addition, the authors detected hot spots of groundwater degradation by anthropogenic activity in the national scale. Analysis of relative contribution of environmental factors further clarified the characteristics in these areas and quantified spatio-temporal trends in groundwater level due to the effects of changes in precipitation and various water uses. Generally, the result showed changes in precipitation had a large effect on changes in groundwater levels until 2000. In contrast, the model clarified human activities have recently had a large impact on groundwater level changes. This trend was particularly conspicuous in river basins with urbanization and mining development such as Orkhon, Kharaa, Tuul, Galba, Ongi, Altain Uvur Govi, and Taats River Basins. This methodology is powerful to resolve future competition for water resources in areas with fewer inventory data that could potentially trigger conflicts between urban, mining, industry, herders and local communities.

Harmful cyanobacterial blooms (HCB) represent a serious threat to aquatic ecosystems due to their production for potent toxins that have negative effects on plant, animal and human health. Although grazing process can be exploited to reduce harmful cyanobacteria in eutrophic waters, the feeding capacity and detoxification capability of the grazer should be considered as key traits of a safe biocontrol agent. In this study, laboratory experiments were conducted to investigate the grazing rate of the ciliate Paramecium jenningsi on toxic Raphidiopsis raciborskii and potential cylindrospermopsin (CYN) degradation during feeding process. P. jenningsi efficiently ingested R. raciborskii cells with high growth (0.1- 0.26 d⁻¹) and grazing rates (0.1-1.4 × 10⁴ cyanobacterial cells ciliate ⁻¹ d⁻¹), varying with the initial ciliate density. CYN concentrations within Raphidiopsis cells displayed an elevation under grazing conditions (5.3-7.2 pg cell⁻¹) compared to control cultures (4.4 pg cell⁻¹). CYN concentrations within the ciliate cells showed a reduction (degradation rate =121-276 pg ciliate⁻¹ d⁻¹) and became undetectable after all Raphidiopsis cells were grazed out, indicating that this ciliate could not accumulate CYN within its body during feeding process. Therefore, P. jenningsi could be used as a safe bioagent for the biocontrol of HCBs in water sources. However, a further in situ study is needed for a possible application of Paramecium species for mitigation of toxic cyanobacteria and their cyanotoxins in the natural environment.