Hydrological Response of the Wami–Ruvu Basin to Land-Use and Land-Cover Changes and Its Impacts for the Future

The evaluation of the hydrological responses of river basins to land-use and land-cover (LULC) changes is crucial for sustaining water resources. We assessed the impact of LULC changes (1990–2018) on three hydrological components (water yield (WYLD), evapotranspiration (ET), and sediment yield (SYLD)) of the Wami–Ruvu Basin (WRB) in Tanzania, using the Soil and Water Assessment Tool (SWAT). The 1990 LULC imagery was used for SWAT simulation, and imagery from 2000, 2010, and 2018 was used for comparison with modelled hydrological parameters. The model was calibrated (1993–2008) and validated (2009–2018) in the SWAT-CUP after allowing three years (1990–1992) for the warm-up period. The results showed a decrease in WYLD (3.11 mm) and an increase in ET (29.71 mm) and SYLD (from 0.12 t/h to 1.5 t/h). The impact of LULC changes on WYLD, ET, and SYLD showed that the increase in agriculture and built-up areas and bushland, and the contraction of forest led to the hydrological instability of the WRB. These results were further assessed with climatic factors, which revealed a decrease in precipitation and an increase in temperature by 1°C. This situation seems to look more adverse in the future, based on the LULC of the year 2036 as predicted by the CA–Markov model. Our study calls for urgent intervention by re-planning LULC and re-assessing hydrological changes timely.

Assessment of water quality based on biological indices of macrobenthos: a river under pressure from tourism activities

Cijulang River is one of the leading ecotourism objects in Pangandaran, West Java Province, Indonesia. However, the river has a variety of activities that can increase the water pollution in the river such as Green Canyon cliffs tourism, ecotourism of mangrove conservation, housing, and industrial siting. Macrobenthos is one of the bio-indicators that can assess the rate of water pollution in rivers, especially their organic pollutants. Therefore, this research aims to determine water pollution status in Cijulang River Tourism by comparing various biotic indices. The study was conducted at four site sampling locations from upstream to downstream in the rainy season period and dry season period using different methods namely, line transect model, water quality assessment by biological indexing (diversity, species dominant, and family biotic), species deficit, and organic measurement. The research showed 5873 macrobenthos and divided into 27 species with an average abundance of 167 ind.m-2 and are mainly dominated by gastropod species Faunus ater (40%). They are extreme species that can live in high organic pollution and water salinity. This divided the research of quality water assessment of Cijulang River into three categories as follows: slightly polluted (score 36-46) at Green Canyon site, moderately polluted (score 50-60) at Boat Shelter and Muara Cijulang location, and highly polluted (score 66) at Nusawiru site.Keywords:RiverBio-indicatorOrganicAquatic pollution

DEFINIÇÃO DAS UNIDADES DE RESPOSTA HIDROLÓGICA NA BACIA HIDROGRÁFICA DO RIO SANTA MARIA- RS

O modelo hidrológico Soil and Water Assessment Tool (SWAT) representa um modelo computacional que conjuga uma série de parâmetros físicos e permite simular diversos cenários com variadas condições de manejo do solo e de uso da terra. Este trabalho apresenta uma discussão sobre o método de geração e as características de cada Unidades Hidrológicas geradas no modelo na bacia hidrográfica do rio Santa Maria. A partir das sub-bacias se estabelece os cruzamentos espaciais dos dados de solos, uso da terra, declividade, gerando novas delimitações espaciais chamadas Unidades de Resposta Hidrológica (URH). Para as classes de declividade da área de estudo, foram definidos os limites de 5 e 15%. O mapa base de solos é do IBGE com descrições dos boletins técnicos no Ministério da Agricultura. O uso da terra do IBGE do ano de 2010, sendo que os tipos de usos foram relacionados aos tipos já cadastrados no banco de dados do ArcSWAT. As URHs representam uma combinação do tipo de solo, declividade, uso da terra. Cada sub-bacia apresenta unidades hidrológicas características. A análise das características da Bacia Hidrográfica do Rio Santa Maria permitiu avaliar que as unidades de respostas hidrológicas geradas representam de forma satisfatória as heterogeneidades presentes.

Measures to Provide Settlements with Quality Drinking Water: Assessment of the Potential by the Example of the Odessa Agglomeration

The rapid urbanisation of the settlements of the Odessa agglomeration has negatively affected the quality of the drinking water that is transported to consumers. The purpose of this study was to determine the most effective measures to provide settlements with quality drinking water. In order to achieve this goal, possible options for measures were considered, and an assessment and comparative analysis of the potential of the proposed options were executed. The most effective measures were evaluated on two criteria: compliance with the principles of sustainable development and whether the measures were effective, reliable and comfortable for consumers when implemented. The factors that influenced the decision-making were the situation and conditions of the implementation of the measures, laboratory tests of the source water and laboratory tests of the water after the treatment process and consumer awareness of participation. The findings demonstrated that a measure was effective if it met the stated criteria. The results of the study are planned to be used as reference material in the elaboration of an integrated plan for the development of settlements, for decision-making in the organisation of recreation and health-related areas and for other resource planning activities.

Application of Soil Water Assessment Tool (SWAT) Model in Analyzing Nitrogen Transport Inside the Narmada River Basin

The Narmada River is one of the largest rivers in Western India encompassing a watershed area of 92,672 km2. It is one of the most important rivers for water needs of the state of Gujarat, Maharashtra, and Madhya Pradesh. The climate of the basin is humid and tropical but region surrounding this river watershed is predominantly dry and resembles semi-arid conditions. The population inside the states covering this watershed increased by an average of 23% from 1991 to 2011 causing multitude of water scarcity and water quality deterioration issues. These problems were caused by increase in sewage waste and untreated industrial discharge dumped into the river stream along with chemical fertilizers washing off from the farmlands flowing into the river. While there are several studies that model the watershed hydrology and water balance components, there has been no study that analyses the transport of nutrients inside the watershed. This study aims at using a semi-distributed hydrological model—Soil Water Assessment Tool (SWAT) to model the nitrogen (NO2 + NO3) transport and distribution inside the basin for 2001–2019. Nutrients and discharge data from Central Water Commission (CWC) of India were used to build this model along with other required input forcing obtained through remotely sensed datasets. We found that the subbasins near boundary of the Narmada watershed are experiencing significant increase in nitrogen concentrations at an estimated rate of 0.0001–0.002 mg/L/yr. The potential reason for such increase is high rate of conversion of forested land to agricultural land causing usage of fertilizers that are rich in nitrogen.

The Impact of the Changes in Climate, Land Use and Direct Human Activity on the Discharge in Qingshui River Basin, China

Climate, land use and human activity have an impact on the Qingshui River in Chongli County. The Soil and Water Assessment Tool (SWAT) was used to separately analyze the contributions of climate, land use and direct human activity on the discharge variations. The results indicated that human activity had been the dominant factor for the discharge decrease, while climate and land use change had a positive influence on the discharge increase. The contributions of these three factors were −56.24%, 38.59% and 5.17%, respectively. Moreover, on the seasonal scale, the impact of those factors was consistent with their impact on the annual scale. Human activity was the main factor for discharge decrease in the summer, the contribution accounting for −77.13%. Due to the over-extraction of groundwater for irrigation and use in the mining industry, the discharge showed a decreasing tendency, which has the potential to place stress on sustainable water use in the future. The result of the study may contribute to the optimization of water resource allocation and management.