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  • Open access
  • 214 Reads
Stable water isotopic evidence for the moisture source and composition of surface runoff in Ladakh, upper Indus river basin (UIRB)

Stable water isotopic analysis of oxygen and hydrogen (δ18O and δ2H) in stream waters, glacier melt and precipitation were used to investigate hydrological pathways and residence times in snow and glacier dominant mountainous sub-basins of Ladakh (UIRB). A significant spatial and temporal variation in precipitation, stream water and glacier melt samples of Ladakh (UIRB) was observed. The δ18O and δ2H values of precipitation, stream water and glacier melt varied from −16.8‰ to −11.2‰, ₋16.8‰ to ₋11.2‰ and −15.3 to −11.4‰ for δ18O and −124‰ to −83‰, ₋124‰ to ₋83‰ and −112 to −70‰ for δ2H. The depleted isotopic values observed in January and enriched in July with drop in the month of august is attributed to temporal changes in ambient temperature, precipitation amount and change in source of moisture. The average altitude effect of stream water is much higher than precipitation and glacier melt. Monthly δ18O and δ2H values of glacier melt were enriched May and depleted in September. The Local Meteoric Water Line (LMWL) of stream water in Ladakh (UIRB) including tributaries and nallahs is δ2H = (7.8±0.1) ˟ δ18O+ (15±1.9) with lower slope than GMWL but higher than LMWL of Ladakh (UIRB). The results suggest that the snow and glacier melts dominantly controls the annual stream flow with average snowmelt of (29%), glacier melt (39%) and rainfall (21%) respectively. The estimated MRT varied from 7.2 to 13.8 months, the longest MRT for the Suru and Nubra sub-basin is ascribed to its complex topography (increasing snow lag) and large size than the other sub-basins. The MRT for the Dras sub-basin is shorter (7 months) owing to its simple topography and carbonate terrain, which facilitates the runoff.

  • Open access
  • 71 Reads
Modelling external risk to agricultural development projects using a Reconnaissance drought (RDI) and Standardised Precipitation indices (SPI)

Drought is defined as a recurrent feature of climate that involve deficiency of precipitation over an extended period resulting in water shortages that have adverse effects on economy, environment and humans and their health. The probability of drought impacts varies widely depending upon drought duration, frequency and severity, baseline population vulnerability, existing health and sanitation infrastructure, and available resources with which to mitigate impacts as they occur. This natural climate feature adversely leads to poor crop yields. The current study aims at charactering drought for proactive management and mitigation strategies to be applied. The study used standardised precipitation (SPI) and reconnaissance drought (RDI) indices to model the behaviour of drought in the study area. The key findings revealed the study area under frequent, severe to extreme drought events. The study recommends that water users and all other relevant stakeholders adopt mitigation strategies such as use of water sparingly, use of drought-resistant crop cultivars and others.

  • Open access
  • 109 Reads
Nature-Based Solutions: Construction Method of Major Drainage System in Plain Lake-type Cities

As a typical fast-growing plain city with the title of “city of hundreds of lakes”, Wuhan, Hubei Province in China, boasts abundant regulating and storing water space. However, this city has suffered from frequent waterlogging and unbalanced storage due to rapid urbanization. To tackle the issue, this study inspired by the idea of “Nature-Based Solutions” (NBS). Taking the major drainage system of Wuhan as an example, it explored the identification and construction of storage and drainage area as well as the planning strategies in the city scale, based on a sustainable urban stormwater system cycle compatible with artificial deployment and natural stormwater process. The stormwater process is simulated with numerical inverse method. Then the drainage network and the natural force get a balance in the system. The result showed that: 1) With the SCS-CN model and surface equal volume filling method, the spaces storing excess surface runoff were identified under the geography and storm recurrence interval; 2) Combining the data of construction land, actual submergence area, and waterlogging points, the major drainage system with emphasis on the restriction of surface elevation were organized. 3) The “storage and drainage function area of major drainage system” was proposed as a NBS. The hierarchical distribution was adopted for layout optimization of urban land use in Wuhan—include the area of storage and drainage, area of strengthened self-drainage, area of waterlogging reduction, and area of low intensity development. Furthermore, it also offered references to the identification and improvement of waterlogging risk points of public facilities in built area.

  • Open access
  • 160 Reads
Spatio-temporal variability in glacier melt contribution in Bhagirathi river discharge in the headwater region of Himalaya

The Himalayan glaciers are one of the significant sources of Indian river systems. In recent times, a major question is being raised about the melting of glaciers and how it will impact river flows in the downstream regions. The Gangotri glacier has also attracted global attention due to the rapid retreat rate. Because of this, the present study has been carried out on the Gangotri glacier, which is the longest glacier located in the Bhagirathi river basin in north India, to understand the dynamics of the glacier and its melting contribution to the river water. In the present study, we collected water samples from the snow/ice, river, and rainfall for isotopic analysis from 2016 to 2018. We observed seasonality in δ18O and δ2H values of rainfall and river water in the Bhagirathi river basin. The isotopic values of rainfall range from -11.6 ‰ to 2.7 ‰ for δ18O, and from -94.8 ‰ to 38.5 ‰ for δ2H during pre-monsoon (April to June), and from -20.6‰ to -4.2 ‰ for δ18O, and from -155.6‰ to -21.9 ‰ for δ2H during monsoon (July to September) season. The river water ranges from -12.8 ‰ to -10.8 ‰ for δ18O, and from -86.3 ‰ to -72.9 ‰ for δ2H during the pre-monsoon, and from -19.0 ‰ to -12.4 ‰ for δ18O, and from -141.9 ‰ to -86.9 ‰ for δ2H during monsoon season. We used a tracer-based hydrograph separation approach to estimate the relative contribution of various river discharge sources. Our results suggest seasonality in relative contribution. The estimated snowmelt contribution is about ~58%, ice melt is ~36%, and surface runoff is ~6%, due to the variability in local climate and temperature in the Himalayan region.

  • Open access
  • 118 Reads
Investigating the socio-economic impacts of climate-induced drought risks on resettled women farmers in Mashonaland Central Province, Zimbabwe

Climate change induced drought has affected the lives of many farmers across the world especially in sub-Saharan Africa where many Farmers rely on rain-fed agriculture. . The aim of this study is to investigate the social and economic impacts of drought on the resettled women farmers, in Zimbabwe, a country that has been devastated by recurrent drought exacerbated by climate change. The women farmers, like their male counterparts were resettled in various settlement schemes, in the post independent Zimbabwe. The resettlement programmes were conducted to address the socio-economic imbalances between the white farmers and the majority black subsistence population. Both male and female were given the opportunity to acquire land; however, for the purpose of this study focus is given to women because of gender inequalities and the historical background of the patriarchal society in Zimbabwe and Africa in general. Women were not allowed to own land, therefore the post-independence resettled women farmers were selected based on their higher levels of vulnerability to climate change-induced drought. The exact numbers of resettled women was not easily available from the provincial department of agriculture, however using the specific their demographic characteristics such as similar type of crops grown, livestock reared and the hectares of their farms including the issue that their agricultural activities are in the same natural farming zone a sample of 267 participants was used. Convergence parallel mixed method design was applied in the study. A multi-sampling technique was used, for purposively selecting three out of seven districts in Mashonaland Central province, namely Bindura, Shamva and Muzarabani. This was followed by stratified random sampling and a simple random sampling which was used for the selection of interview participants. Qualitative data was analysed by extracting themes and quantitative data was analysed using the exploration of demographics using PIVOT tables (MS excel), reliability test analysis (using SPSS V25 IBM) and descriptive statistics per latent variable. The results showed that the nutrition of the women farmers and their families was diminished, some of the children drop out of school because the women farmers were not able to pay school fees. The women farmers were not able to buy inputs for the next farming seasons and were not able to pay back loans. The study recommended that the government and other organisations should offer financial assistance, conduct more drought awareness campaigns, and encourage women farmers to have alternatives sources of livelihood.

  • Open access
  • 146 Reads
Published: 12 November 2020 by MDPI in The 5th International Electronic Conference on Water Sciences session Poster

This study aims to assess the impact of 2010-2011 flash floods on the crop production of Sanghar—an eastern district of Sindh. The population of almost two million is mainly dependent on agriculture. Cotton, sugarcane, and wheat are the main cash crops of the district. In 2010-2011 Sanghar was hit by flash floods after heavy rainfall. These floods adversely affected the crops standing at that time.

However, on the other hand, they increased the fertility of agriculture lands. Satellite images, precipitation data, and Geographical Information System (GIS) tools were used to quantify the effects of floods by mapping pre- and post-floods vegetation cover. Supervised classification was manipulated on Landsat images from 2009 to 2013 to extract vegetation area. The temporal analysis unveils a significant increase in the vegetation cover in the post-flood years. Furthermore, the comparison between pre- and post-flood crop production data collected from the Pakistan Bureau of Statistics, also validated the study results by revealing an increase in crop production.

  • Open access
  • 84 Reads
Hydro-energy suitability of the rivers regarding their hydrological and hydrogeological characteristics

Production of the electric energy from the rivers by using the mini, as well as micro, hydroelectric power plants is a very prospective solution, especially in the rural and isolated areas. Numerous waterways in Croatia and their hydrological and hydrogeological diversity present an opportunity, but also a challenge, for the construction of hydroelectric power plants. Due to the complexity of the water courses hydrology, as well as hydrogeological characteristics, it is very hard to determine an appropriate flow pattern (amount), which will be used as an input value for the sizing of hydroelectric power plants. Such analysis will be provided for real case studies in Croatia with special regard to present geological media - media with intergranular porosity (river Bednja), karstmedia (river Gornja Dobra), and flysch media (river Mirna). Taking into account different geological media increases the possibility of using the presented methodology on other locations in Croatia, as well in the world.

  • Open access
  • 418 Reads
Monitoring Amu Darya river channel dynamics using remote sensing data in Google Earth Engine

River morphological dynamics result from processes involving discharge flow, debris and sediment transport, channel migration, and floodplain erosion and accretion. Understanding the river channel dynamics is an essential component of the development of the most environmentally acceptable and sustainable fluvial projects. In this study, part of the Amu Darya river channel dynamics using remote sensing data have been investigated. For this purpose, satellite imagery from four different periods ten years apart (1990-2000, 2000-2011, 2011-2020), have been used to map and monitor the dynamics of the river over the last three decades. The classification of the images was conducted in Google Earth Engine (GEE) using Landsat imagery. In addition to the river mapping and monitoring, a land cover change detection in the study area has been made. The results showed that the increase in irrigated areas, in the four specified periods was significant and played an important role in increasing the vulnerability of the study area to soil erosion which leads to river channel dynamics. The results showed that the use of Landsat and GEE can be a significant source of updated data for mapping and monitoring river dynamics, with a classification accuracy of the water areas higher than 90%. For future studies, we recommend using satellite imagery with a higher spatial and spectral resolution, like Sentinel.

  • Open access
  • 115 Reads
Landscape pattern effects on surface runoff: Assessment using a hydrologic model in the Fuhe Basin of Poyang Lake Watershed
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A series of urgent issues such as global warming, frequent natural disasters, and water shortages are largely result from heavy human interference and its induced changes of landscape structure. How the landscape pattern variation impacts the surface runoff remains an unsolved issue for watershed water management. In the past decades, the action of ecological environment protection and projects of returning farmland to forests and grasslands have significantly changed the landscape pattern in Fuhe Basin of Poyang Lake watershed, which will inevitably affect the hydrological cycle of the basin. In this study, the SWAT (Soil and Water Assessment Tool) model for the Fuhe Basin was firstly built to predict the runoff depth for the divided 31 subbasins during three periods from 1990 to 1999, 2000 to 2008 and 2009 to 2013. Meanwhile, dynamic changes of landscape pattern were analyzed Based on the land use and cover data in the year of 1990, 2000, and 2008. Finally, the correlations between different landscape indicators and surface runoff were quantified over subbasins using Spearman Correlation analysis.

Results showed that the SWAT model is applicable in Fuhe Basin with R2 (correlation coefficient) and Ens (Nash-Sutcliffe efficiency coefficient) larger than 0.85 for runoff prediction. Based on the land use and cover data in the year of 1990, 2000, and 2008, the landscape index were calculated. The fragmentation degree increased first and then decreased during the two transition periods. The landscape patches shape became more complicated and connectivity of different landscapes decreased and then increased, among which the forest and paddy field have greatest fragmentation degree. Forest has a larger dominance degree, which was highly connectable to patches of other various types of landscape. According to the changes of landscape pattern from 1990 to 2008, the smaller fragmentation degree, more complex patch shape, and more uneven distribution of landscape patches led to more precipitation interception and runoff reduction.

From the perspective of the landscape type, the landscape area ratio (PLAND) of dry land, paddy field, water area, urban and rural construction land patches has a significantly positive correlation with surface runoff, while PLAND and FRAC_AM (Area Weighted Patch Fractal Dimension) index of forestland have a significantly negative correlation with surface runoff. The complexity of forestland patch shape strengthened the interception of rainfall and plant transpiration of land surface, which would reduce water yield. The expansion of urban impervious area, aggravating landscape fragmentation, reduced runoff interception and increased surface runoff, which can be indicated by positive relation with PLAND and FRAC_AM index of urban construction. Deeply understanding surface runoff alternations, induced by landscape patterns changes, would provide theoretical support for solving the problems of sustainable utilization of water resources, but also offers best management practices (BMPs) for land management.

  • Open access
  • 88 Reads
Analysis on ecological environment changes and driving factors of Danjiangkou reservoir under the influence of Water Diversion Project
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The South-to-North Water Diversion (SNWD) Project is the largest inter basin water transfer project in the world. Danjiangkou Reservoir is water source of Middle Route Project of the South-to-North Water Diversion Project. Since the water was opened in December 2014, the problem of water shortage in northern China has been greatly alleviated. However, some studies have shown that the SNWD Project greatly reduces the available water resources in the downstream of the reservoir and affects the vegetation growth and agricultural production in the downstream and upstream. On the other hand, the problems of permanent land occupation, water storage and resettlement caused by the SNWD Project have caused many ecological and environmental problems in the reservoir area, and have a profound impact on the whole basin. It is of great value to evaluate the changes of ecological environment in the basin under the SNWD Project, which is of great value for guiding the ecological construction and development of the basin and scientific water transfer, and also provides a reference for the scientific identification of the basin ecological environment response mechanism under the influence of large-scale water conservancy projects. At present, before and after the Middle Route Project of SNWD Project, the quantitative research on the change characteristics and response law of the overall ecological environment in Danjiangkou reservoir area is lack. Therefore, this study takes Danjiangkou reservoir and Han River Basin as the research object, calculates and analyzes the spatial-temporal dynamic changes of reservoir water volume, watershed vegetation and ecosystem services value before and after water diversion, explores the influence of water volume on the changes of vegetation and ecosystem services value, with the help of land use, climate, socio-economic data to understand the driving forces of vegetation and ecosystem services value change, quantitatively evaluate the impact of SNWD Project on the ecological environment of the river basin, and scientifically identify the ecological environment of the river basin from the two aspects of basic data support and theoretical basis. The response characteristics of the basin ecological environment to the SNWD Project are scientifically identified, which lays the foundation for improving the incentive system of ecological environment protection.