An ecohydrological approach to assess water provisioning and supporting ecosystem services in the Budhabalanga River Basin, India.

Rivers are vital and complex natural systems that provide a wide range of ecosystem services. This study presents a methodology for assessing the riverine provisioning and supporting ecosystem services, whose applicability has been demonstrated over the Budhabalanga River Basin of India. The Soil and Water Assessment Tool (SWAT) is used to generate streamflow time series at various ungauged sites, and then the streamflow is characterized for the evaluation of provisioning services. Further, the diversity and abundance of macroinvertebrates, along with the Lotic-invertebrate Index for Flow Evaluation (LIFE), is used to study the riverine supporting ecosystem services. The streams show intermittent behavior and strong seasonality for low flows, which limits the water availability, particularly during pre-monsoon season. The Baseflow Index (BFI) is greater than 0.6, indicating that groundwater contributes more than 60% of the total streamflow. Interestingly, despite the high BFI, the streams did not conform to the prevailing opinion that a greater baseflow contribution results in a later commencement of the low-flow period in the hydrological year. Furthermore, the study depicts significant variations in the diversity and abundance of the macroinvertebrates across the various sampling sites. However, the LIFE score across the sites remained consistent within a narrow range, i.e., 8 to 9, suggesting a steady supply of supporting ecosystem services. The results of the study can help the policymakers towards an informed decision making and the simplistic methodology proposed in this study can be replicated in other river basins for identifying vulnerable watersheds and prioritizing management actions.

Land use and land cover dynamics in the Upper Ganga Riverine Wetland: unraveling ecosystem services over two decades.

Anthropogenic activities have drastically transformed natural landscapes, profoundly impacting land use and land cover (LULC) and, consequently, the provision and functionality of ecosystem service values (ESVs). Evaluating the changes in LULC and their influence on ESVs is imperative to protect ecologically fragile ecosystems from degradation. This study focuses on a highly sensitive Upper Ganga riverine wetland in India, covering Hapur, Amroha, Bulandshahr, and Sambhal districts, which is well-known for its significant endemic flora and fauna. The study analyzes the subtle variability in ecosystem services offered by the various LULC biomes, including riverine wetland, built-up, cropland, forest, sandbar, and unused land. LULC classification is carried out using Landsat satellite imagery 5 and 8 for the years 2000, 2010, and 2020, using the random forest method. The spatiotemporal changing pattern of ESVs is assessed utilizing the value transfer method with two distinct value coefficients: global value coefficients (C14) for a worldwide perspective and modified local value coefficients X08 for a more specific local context. The results show a significant increase in built-up and unused land, with a corresponding decrease in wetlands and forests from 2000 to 2020. The combined ESVs for all the districts are worth US $5072 million (C14) and US $2139 million (X08) in the year 2000, which declined to US $4510 million (C14) and US $1770 million (X08) in the year 2020. The sensitivity analysis reveals that the coefficient of sensitivity (CS) is below one for all biomes, suggesting the robustness of the employed value coefficients in estimating ESVs. Moreover, the analysis identifies cropland, followed by forests and wetlands, as the LULC biomes most responsive to changes. This research provides crucial insights to stakeholders and policymakers for developing sustainable land management practices aimed at enhancing the ecological worth of the Upper Ganga Riverine Wetland.

Complexities of the urban drinking water systems in Ethiopia and possible interventions for sustainability.

Rapid urbanization in developing countries has imposed threats and challenges to basic urban infrastructures like drinking water, transportation, and energy systems. The existing urban drinking water systems (UDWS) are highly stressed and unsustainable, particularly under changing hydroclimatic conditions, population growth, changing socioeconomic conditions, government decisions, and various policies. This study focuses on the complexities of UDWS in Sub-Saharan African countries, especially in Ethiopia. The objective of this study is to investigate the issues and challenges of urban drinking water systems (UDWS) in Ethiopia, specifically, to assess the gap between water supply and demand, water loss/non-revenue water, environmental, technical, institutional, and governance, etc. and propose sustainable interventions to deal with such issues so as to improve. For this purpose, a mix of methods involving primary data (including key informant interviews, field observations, and field measured data) and secondary data (including published articles, books, various reports, and design documents), as well as various computer-aided applications (mainly, ArcGIS and WaterGEMS) are used to collect data. The issues are deliberated through the UDWSs of Addis Ababa, Adama, Mekelle, and Dire Dawa cities in Ethiopia. Complexities like water shortage, high and low pressure in the water distribution network (WDN), non-revenue water (NRW)/water loss, source pollution, ineffective policies and governance, and weak institutions are the main challenges to Ethiopian cities' water utilities. Further, the case study noticed that in Addis Ababa alone, potable water is only accessible to 66% of the city population. A significant water supply deficit was observed in Mekelle city, where only half of the city population has access to potable water from the system. Additionally, in Addis Ababa, Adama, Mekelle, and Dire Dawa, above 35% of the freshwater produced is either NRW, unaccounted for, or lost, which is significantly higher than the upper 25% limit suggested by the World Bank. Therefore, it is recommended to adopt certain sustainable interventions, such as integrated water resource management, installing appurtenances like pressure-reducing valves, check valves in the WDN, controlling and monitoring of WDN through supervisory control and data acquisition and Internet of Things, effective and long-term planning and policy, etc. It is felt that the study will help the decision-makers and the operators of the UDWS utilities to run the water supply schemes in a sustainable manner. Supplementary Information: The online version contains supplementary material available at 10.1007/s10668-022-02901-7.

A comparative study of morphometric, hydrologic, and semi-empirical methods for the prioritization of sub-watersheds against flash flood-induced landslides in a part of the Indian Himalayan Region.

The flash flood-induced erosion is the primary contributor to soil loss within the Indian Himalayan Region (IHR). This phenomenon is exacerbated by a confluence of factors, including extreme precipitation events, undulating topographical features, and suboptimal soil and water conservation practices. Over the past few decades, several flash flood events have led to the significant degradation of pedosphere strata, which in turn has caused landslides along with fluvial sedimentation in the IHR. Researchers have advocated morphometric, hydrologic, and semi-empirical methods for assessing flash flood-induced soil erosion in hilly watersheds. This study critically examines these methods and their applicability in the Alaknanda River basin of the Indian Himalayan Region. The entire basin is delineated into 12 sub-watersheds, and 13 morphometric parameters are analyzed for each sub-watershed. Thereafter, the ranking of sub-watersheds vulnerability is assigned using the Principal Component Analysis (PCA), compounding method (CM), Geomorphological Instantaneous Unit Hydrograph (GIUH), and Revised Universal Soil Loss Equations (RUSLE) approaches. While the CM method uses all 13 parameters, the PCA approach suggests that the first four principal components are the most important ones, accounting for approximately 89.7% of the total variance observed within the dataset. The GIUH approach highlights the hydrological response of the catchment, incorporating dynamic velocity and instantaneous peak magnifying the flash flood susceptibility, lag time, and the time to peak for each sub-watershed. The RUSLE approach incorporates mathematical equations for estimating annual soil loss utilizing rainfall-runoff erosivity, soil erodibility, topographic, cover management, and supporting practice factors. The variations in vulnerability rankings across various methods indicate that each method captures distinct aspects of the sub-watersheds. The decision-maker can use the weighted average to assign the overall vulnerability to each sub-watershed, aggregating the values from various methods. This study considers an equal weight to the morphometric, hydrological GIUH, and semi-empirical RUSLE techniques to assess the integrated ranking of various sub-watersheds. Vulnerability to flash flood-induced landslides in various sub-watersheds is categorized into three classes. Category I (high-priority) necessitates immediate erosion control measures and slope stabilization. Category II (moderate attention), where rainwater harvesting and sustainable agricultural practices are beneficial. Category III (regular monitoring) suggests periodic community-led soil assessments and afforestation. Sub-watersheds WS11, WS8, WS5, and WS12 are identified under category I, WS7, WS4, WS9, and WS6 under category II, and WS1, WS3, WS2, and WS10 under category III. The occurrence of landslides and flash-flood events and field observations validates the prioritization of sub-watersheds, indicating the need for targeted interventions and regular monitoring activities to mitigate environmental risks and safeguard surrounding ecosystems and communities.

Hydrological modelling of a snow/glacier-fed western Himalayan basin to simulate the current and future streamflows under changing climate scenarios.

Himalayan rivers are the paramount source of water supply to millions of people in northern India for drinking, irrigation and hydropower generation. Several researches reported that the hydrological regime of these Himalayan rivers is vulnerable to climate change. In order to understand the hydrologic response of their headwaters and examine the climate change impacts on streamflow, a hydrological modelling study is carried out in the upper part of the Satluj river basin in western Himalaya by using a temperature index based SWAT (Soil Water Assessment Tool) model. The model performed well for both calibration (years 1986-2000) and validation (2001-2005) periods against the observed daily streamflow at Rampur (R2 ≈ 0.9 and NSE ≥ 0.85). The study reveals that having a larger snow covered area, the snowmelt runoff is the major contributor to the Satluj river discharge at Rampur that comes out to be about 68-71% of the average annual water yield of about 600 mm. The actual evapotranspiration comes out to be about 14% of precipitation. The water yield of the basin is about 50% of the precipitation, for which the major part is generated in early summer. Further, to study the climate change impact on future streamflow, the downscaled data of CORDEX CCSM4 under two Representative Concentration Pathways (RCP4.5 and RCP8.5) scenarios are used. The bias correction is applied at point level to remove biases from future time series of downscaled data and subsequently loaded into the SWAT model to simulate the future streamflows at the end of the century. The future climate variability in terms of precipitation and temperature exhibited that the climate in the region would become wetter and warmer. A 14% to 21% of increase in annual precipitation is predicted towards the end of the century from the current average annual precipitation of about 420 mm under RCP4.5 and RCP8.5, respectively. Similar to precipitation, the temperature will also be increased by 2.18 °C to 5.71 °C (in both the RCPs) than the current temperature values. The changed climate conditions in future are transformed into the possible range of stream flows using the SWAT model and found that the future climate would increase the streamflow by over 11%-19% at the end of the century under RCP4.5 and RCP8.5 scenarios, respectively. The outcome of this study can be used to develop the suitable strategies for sustainable water management in the region.