Surface Water Resources Research Articles

Hydrochemical Characteristics and Factors of Surface Water and Groundwater in the Upper Yongding River Basin

The Yongding River basin is an important water conservation and ecological barrier area in the Northwest of Hebei Province. Reduced runoff and deterioration of the water environment in this area have become increasingly prominent under the effects of climate change and intensive human activities. Clarifying the chemical characteristics and factors of surface water and groundwater in the upper Yongding River basin can provide data and support for the sustainable use of water resources. Stable isotopes of hydrogen and oxygen (δ2H and δ18O) were used to study the sources of surface water and groundwater. Mathematical statistics and hydrogeochemical methods were then used to analyze the regional hydrogeochemical processes and factors of surface water and groundwater. The results showed that precipitation was the main source of surface water and groundwater. Under the effects of natural factors and human activities, the Yang River and Sanggan River basins exhibited significant differences in surface water chemistry. The sub-basins were ranked by ion concentration as follows: Sanggan River>Yang River. The main cation and anions of the Sanggan River basin were Na+, Cl-, and SO42-, while in the Yang River basin, Ca2+ and HCO3- were the most common. The water chemistry of the Sanggan River exhibited greater variation than that of the Yang River. Surface water chemistry were mainly controlled by mineral dissolution and evaporation, but human activities were reflected in different sub-basins. Surface water in the Sanggan River basin was affected by industrial wastewater discharge, while that of the Yang River basin was affected by agricultural production and cities. However, the continuous increase of Cl- and SO42- concentrations, caused by industrial wastewater discharge and acid rain, was the limiting factor for sustainable use of surface water resources. In future, surface water in Sanggan River basin should be used with consideration to the effects of both total salinity and chemical composition of the water, while in Yang River, a focus should be placed on total salinity. The use of surface water resources in accordance with local conditions is an effective measure for the sustainable use of water resources and the restoration of groundwater levels in this region.

Short-term forecasting of monthly water consumption in hyper-arid climate using recurrent neural networks

Freshwater supply is a major challenge in regions with limited water resources and extremely arid climatic conditions. The objective of this study is to model the monthly water demand in Kuwait using the nonlinear autoregressive with exogenous input (NARX) neural network approach. The country lacks conventional surface water resources and is characterized by extremely arid climate. In addition, it has one of the fastest growing populations. In this study, linear detrending is performed on the water consumption time series for the period from January 1993 to December 2018 to eliminate the influence of population growth before application to the NARX model. Monthly temperature data are selected as exogenous input to the NARX model, because they are strongly associated with the water consumption data. Correlation analyses are performed to determine the input and feedback delays of the NARX model. The results demonstrate that the recurrent NARX model is efficient and robust for forecasting the short-term water demand, with a Nash-Sutcliffe (NS) coefficient of 0.837 in the validation period. Seasonal model assessment shows that the model performs best during the critical summer season. The NARX-based recurrent model is established as a powerful and promising tool for predicting urban water demand. Thus, it can efficiently aid the development of resilient water supply plans.

Equitable Allocation of Surface Water and Groundwater Resources in Foumanat Irrigation Area with Optimization Approach

Equitable Allocation of Surface Water and Groundwater Resources in Foumanat Irrigation Area with Optimization Approach

Hydrogeophysical Study of Sub-Basaltic Alluvial Aquifer in the Southern Part of Al-Madinah Al-Munawarah, Saudi Arabia

Groundwater is extremely important in a water-scarce country such as Saudi Arabia, where permanent surface water resources are absent. Sustainable and future developments plans are essentially relying on the clear understanding of water resources. To evaluate the water resources in arid countries, the groundwater should be quantified through either traditional or scientifically advanced techniques. Aquifer characteristics, particularly the hydraulic conductivity and transmissivity, are essential for the evaluation the aquifer properties as well as the management and development of groundwater modelling for specific aquifers. The present study aims to evaluate the sub-basaltic alluvial aquifer in the northern part of Harrat Rahat, south of Al-Madinah city, and then estimates the principal aquifer’s hydraulic parameters based on the interpreted 1D resistivity-depth models along the study area. For that, 49 Vertical Electrical Soundings (VES’s) utilizing a Schlumberger electrode array were performed along the southern part of Al-Madinah city. The resistivity of the water-bearing formation, thickness, porosity, hydraulic conductivity, and transmissivity parameters were calculated along the measured longitudinal profile from the interpreted VES data. The estimated porosity, hydraulic conductivity, and transmissivity were achieved along the whole profile with average values of 0.2, 3.5 m/day, and 369.6 m2/day, respectively. The resulting transmissivity values from the VES models were compared with those of previous pumping test measurements carried out in the area and a reasonable correlation between the two data sets was observed. These results indicate that surface geoelectrical resistivity techniques may provide an alternative, rapid, and cost-effective method of estimating the aquifer hydraulic parameters where pumping data is rare or unavailable.

A NEW WAY OF USING THE SPIDER DIAGRAM METHOD IN HEAVY METAL POLLUTION STUDIES FOR NEAR-SURFACE GEOPHYSICS AND THE OTHER EARTH SCIENCES

In this study, a new way of using the Spider Diagram (SD) method has been shown in the investigation of the pollution spread and pollutant species caused by heavy metal-containing leachate in soil ground. Thus, it has been shown that this method can be used in conjunction with the results of earth science studies and its contribution to interpretation was emphasized. Because today, heavy metals in leachate water are an important environmental problem. It was determined that SD and geophysical methods could be used together in studies investigating this pollution. The heavy metal-containing leachate may contaminate the agricultural/non-agricultural soils/grounds or underground/surface waters by spreading in the permeable geological unit. This pollution spread and pollutant species can be analyzed by geochemistry (soil samples) studies. In addition, the horizontal-vertical boundaries of this pollution and the direction of pollution can be determined by geophysical methods. The results of soil analysis can also be interpreted using the SD method. However, it has been determined that this method can be used to interpret with geophysical results. This comparison has been found to contribute to the geophysical results in interpretation and it has been observed that it strengthens the geological interpretations. As a result, it is shown that SD method is a method that allows evaluating a large number of data in a short time and it can be used together with earth science methods. If these methods are used together in heavy metal pollution investigations, it has been shown whether the pollution in the soil is caused by the leachate or the bedrock unit, and in addition, whether the underground and surface water resources in the region are under the threat of pollution caused by leachate. It was thought that such a study would also be useful in Environmental Impact Assessment (EIA) studies.

Community Water Demand and Sustainable Water Supply Planning in Nigeria: A Review

The purpose of this study is to review past works in water demands and sustainable water supply planning in Nigeria as reported by many researchers and to determine how to improve the water supply infrastructure sustainably. Nigeria is endowed with abundant surface water and ground water resources. The mean annual rainfall along the coast in the south east is 4 800 mm while it is less than 500 mm in the north east. These water sources are not tapped to the fullest and most of them are polluted and unsafe for use, resulting to scarcity of potable water in most communities. Water crisis is prevalent in most cities and this is further exacerbated by deteriorating infrastructure, political instability, and poorly regulated water laws. The result of the water crisis has led to detrimental consequences for its citizens as child mortality and water-borne disease-related deaths have grown exponentially. Unsuitability of water distribution facilities, quantity of water transported, too much walking distance, long lines at water points, poor maintenance and inadequate bulk water development brought about inefficiency of the facility. The water demand and supply in some countries in the world and many towns in Nigeria were reported. The method adopted in the study involved the use of journals, books and other related literature. The result showed that water supply systems in most places in the country are in poor state, unorganized and incomplete. All countries highlighted showed many problems at various degrees in provision of the facility. Attempt was made to fill some gaps in the literature. Public enlightenment, financing, monitoring, maintenance and juicy annual remuneration packages for best water users are recommended as powerful tools towards sustenance of the water supply infrastructure.

Quantitative microbial human exposure model for faecal indicator bacteria and risk assessment of pathogenic Escherichia coli in surface runoff following application of dairy cattle slurry and co-digestate to grassland

Animal waste contains high numbers of microorganisms and therefore can present a potential biological threat to human health. During episodic rainfall events resulting in runoff, microorganisms in the waste and soil may migrate into surface runoff, contaminating surface water resources. A probabilistic human exposure (HE) model was created to determine exposure to faecal indicator bacteria (FIB): total coliforms (TC), E. coli and enterococci following application of bio-based fertiliser (dairy cattle slurry, digestate) to grassland; using a combination of experimental field results and literature-based data. This step was followed by a quantitative microbial risk assessment (QMRA) model for pathogenic E. coli based on a literature-based dose-response model. The results showed that the maximum daily HE (HEdaily) is associated with E. coli for unprocessed slurry (treatment T1) on day 1, the worst-case scenario where the simulated mean HEdaily was calculated as 2.84 CFU day −1. The results indicate that the overall annual probability of risk (Pannual) of illness from E. coli is very low or low based on the WHO safe-limit of Pannual as 10 −6. In the worst-case scenario, a moderate risk was estimated with simulated mean Pannual as 1.0 × 10 −5. Unpasteurised digestate application showed low risk on day 1 and 2 (1.651 × 10 −6, 1.167 × 10 −6, respectively). Pasteurised digestate showed very low risk in all scenarios. These results support the restriction imposed on applying bio-based fertiliser if there is any rain forecast within 48 h from the application time. This study proposes a future extension of the probabilistic model to include time, intensity, discharge, and distance-dependant dilution factor. The information generated from this model can help policymakers ensure the safety of surface water sources through the quality monitoring of FIB levels in bio-based fertiliser.

Application of Drone Technologies in Surface Water Resources Monitoring and Assessment: A Systematic Review of Progress, Challenges, and Opportunities in the Global South

Accurate and timely information on surface water quality and quantity is critical for various applications, including irrigation agriculture. In-field water quality and quantity data from unmanned aerial vehicle systems (UAVs) could be useful in closing spatial data gaps through the generation of near-real-time, fine resolution, spatially explicit information required for water resources accounting. This study assessed the progress, opportunities, and challenges in mapping and modelling water quality and quantity using data from UAVs. To achieve this research objective, a systematic review was adopted. The results show modest progress in the utility of UAVs, especially in the global south. This could be attributed, in part, to high costs, a lack of relevant skills, and the regulations associated with drone procurement and operational costs. The progress is further compounded by a general lack of research focusing on UAV application in water resources monitoring and assessment. More importantly, the lack of robust and reliable water quantity and quality data needed to parameterise models remains challenging. However, there are opportunities to advance scientific inquiry for water quality and quantity accounting by integrating UAV data and machine learning.

Management and Utilization Strategy of Water Resources for Rice Production

Declination of available water resources is threatening the dry season crop production in Bangladesh. Sustainable water management is crucial need to meet future food production. This study was aimed to determine futuristic water management strategy for rice cultivation. Both surface and groundwater is getting scarce in north-west region, whereas abundant of fresh surface water creating opportunities to irrigate dry season crops in south-central region. This study has outlined irrigation management for rice cultivation and groundwater utilization in water scarce area of north-west region. More than 75% of annual rainfall occurred during monsoon and crops other than monsoon often faced water shortage. Timely establishment of T. Aus rice on 01 May accounted average 183 mm supplemental irrigation for north-west and south-west region. Transplanting of T. Aman rice before 24 July found the low risk period of drought and gave about 1 t ha-1 yield advantage than late transplanting after 15 October. Supplemental irrigation in drought year gave up to 26% yield advantage than the rain-fed condition of T. Aman rice in experimental plot. Over exploitation of groundwater by famers for crop cultivation makes the groundwater status worsen. Farmers used 38% excess water than the actual requirement for Boro rice cultivation. For that annual groundwater withdrawal was higher than annual recharge causing groundwater level depletion in most of the districts. Groundwater table went below suction limit of shallow tubewell (STW) during dry season and thus it become unable to operate. Improved distribution system with plastic pipe, buried pipe could save about 25% of irrigation water. Alternate wetting and drying (AWD) irrigation method saved 20-25% water than farmer’s practice. Application of these on-farm water management technologies in Boro rice reduced water demand and made the groundwater balance positive as well as reduced the groundwater withdrawal pressure. On the contrary, irrigation with less saline surface water resources in river and canals of south central regions could expand Boro production and increased land productivity. Intervention of low lift pump with plastic pipe distribution in non-saline tidal areas could increase land productivity. Besides, trapped freshwater in to the canals inside the polders and re-excavation of these canals would make crop intensification. Thus, additional food production could help to achieve sustainable development goal and sustained food security. Bangladesh Rice J. 25 (1) : 37-50, 2021

Microbial modelling of Lake St. Clair: Impact of local tributaries on the shoreline water quality

Fecal contamination of surface water resource is a major health concern primarily due to the potential for pathogenic organisms to be transmitted to human by contaminated water. In lake-wide modelling of large lakes with many sources of microbial contamination, minor contributions from small tributaries are generally ignored. In this study, we applied a three dimensional high-resolution hydrodynamic and water quality model to assess the impact of eight smaller tributaries located on the southern edge of Lake St. Clair on microbial water quality during the summer of 2016. The impact at two beaches and two drinking water intakes located in the nearshore region of the southern edge of Lake St. Clair was considered. Results reveal that the microbial water quality in the nearshore regions close to these eight small tributaries' confluence are significantly affected by one or more of these tributaries. Although this effect is captured by our model with a time-variable or constant decay rates, the use of time-variable decay may be preferable for dynamic simulations over time. The total flow contribution from the smaller tributaries was estimated in the range of 18-35% while that for E. coli concentration was >80%. Three small tributaries were also predicted to account for >70% of the E. coli concentrations at drinking water intakes. For tributaries that do not significantly affect the hydrodynamics in a lake, a new framework is presented to identify approximate influence zones for microbial pollution that can help determine if a given location is likely to be impacted by the inflowing tributaries.

Integrating IHACRES with a data-driven model to investigate the possibility of improving monthly flow estimates

Abstract Estimating the outflow of basins is a critical step in surface water resources planning and management, especially in basins that lack reliable long-term observed data of streamflow. Hydrological models, which can simulate the process of rainfall-runoff, can be used to obtain reliable estimates of streamflow from precipitation data and the physical characteristics of basins. The focus of the present study was to estimate the outflow of 19 sub-basins located in Guilan Province, northern Iran. To achieve this, hybrid models were developed by integrating the IHACRES (identification of unit hydrograph and component flows from rainfall, evapotranspiration, and streamflow) hydrological model with the intelligent-based GMDH (group method of data handling) model. The IHACRES model was calibrated using monthly ground-based precipitation and temperature data as well as satellite-based precipitation data. The lowest and highest Nash-Sutcliffe coefficient (NS) for the IHACRES models were, respectively, 0.14 and 0.68 in the calibration phase and 0.11 and 0.73 in the validation phase. It was also observed that using satellite-based precipitation data reduces NS by 10–75% in the 19 sub-basins under study. After calibrating and validating the IHACRES models, the hybrid models were developed by integrating IHACRES and GMDH models. The lowest and highest NS for the hybrid models were, respectively, 0.23 and 0.81 in the calibration phase and 0.11 and 0.81 in the validation phase. It was observed that, on average, integrating IHACRES and GMDH increases the NS by 44.1% in the calibration phase and 37.0% in the validation phase in comparison with the IHACRES model. According to the NS, the hybrid model had ‘acceptable’ performance in six sub-basins in which the IHCRES model had ‘unacceptable’ performance. It was observed that integrating the IHACRES model with a data-driven model (the GMDH model) can generally improve the simulation results in all sub-basins under study.

Spatio‐temporal heterogeneities in water quality and their potential drivers in Lake Chaohu (China) from 2001 to 2017

AbstractDamage to the water ecosystems and the deterioration of lake water resources may negatively affect the surface water resources, particularly, which of the daily drinking water supply of residents. Therefore, it is particularly important to study the spatio‐temporal heterogeneity of water quality in large lakes. We analysed the data from six sampling sites in Lake Chaohu from 2001 to 2017 and eight sampling sites of the inflow rivers in 2001, 2009 and 2017. The six sampling sites were divided into SG I and SG II through cluster analysis, and the spatio‐temporal changes of the water quality in the Lake Chaohu Basin were studied. The results indicated the following: All nutrient variables had relatively high concentrations in SG II except DO, while SG I had relatively high concentrations of only TN. Besides, the value of Chl a in each group is generally high. On the temporal scale, the changes in the water quality of the lake showed strong seasonality; the nutrient variable (TN, TP, NH4‐N and CODMn) except DO in the inflow rivers is generally higher than that of the lake; the water quality of Lake Chaohu has improved during the study period, and it has also improved to a certain extent compared with that of the late 1980s. Fortunately, parts water quality parameters of Lake Chaohu have improved faster than that of the other four largest freshwater lakes in China. This research result has a certain guiding significance for the prevention and control of large lake water pollution.

Definition of Ecological Flow Using IHA and IARI as an Operative Procedure for Water Management

It is widely recognized that the hydrological regime of natural flow plays a primary and crucial role in influencing the physical condition of habitats, which, in turn, determines the biotic composition and sustainability of aquatic ecosystems. The current hydro-ecological understanding states that all flow components might be considered as operational targets for water management, starting from base flows (including low flows) to high and flood regimes in terms of magnitude, frequency, duration, timing, and rate of change. Several codes have been developed and applied on different case studies in order to define common tools to be implemented for Eflow assessment. This work deals with the definition of an operative procedure for the evaluation of the Eflow monthly distribution to be adopted in a generic watercourse cross-section for sustainable surface water resource management and exploitation. The methodology proposes the application of the Indicators of Hydrologic Alteration methodology (IHA by TNC) coupled to the valuation of the Index of Hydrological Regime Alteration (IARI by ISPRA) as an operative tool to define the ecological flow in each monitoring cross-section to support sustainable water resource management and planning. The case study of the Agri River in Basilicata (Southern Italy) is presented. The analyses were carried out based on monthly discharge data derived by applying the HEC-Hydrological Modeling System at the basin scale using the daily rain data measurements obtained by the regional rainfall gauge stations and calibrated through the observed inlet water discharge registered at the Lago del Pertusillo reservoir station.

RETRACTED ARTICLE: Image classification-based groundwater pollution prediction and regional economic collaborative innovation

At present, as a nonrenewable resource, water resource has become an important living condition of human society and the whole ecosystem. As an important part of the whole social water resources system, groundwater resources play a very important role in human society. Due to the scarcity of surface water resources and the aggravation of pollution, human beings began to exploit the relatively clean underground water. In China, groundwater accounts for about one third of all water resources, and is one of the important water sources for people’s living water, social production, and development. At present, many cities in China are using groundwater as industrial and domestic water. Because of the nature of groundwater, when it is polluted, it is difficult to treat and recycle, which directly affects people’s water use and social development. Therefore, we propose a groundwater pollution prediction method based on image classification. Supply chain coordination based on the analysis of the basic principles of regional economic innovation system, this paper focuses on the problems related to the supply chain system coordinated with the development of regional economic innovation. By creating a supply chain system and combining with the characteristics of regional economic development, the decentralized system can be integrated across different regions, departments and companies. In this paper, through the realization of the optimal allocation of production factors resources, to achieve the value reconstruction and create the added value of regional economy and industrial collaborative innovation, effectively promote the healthy and scientific development of China’s social economy.

Regional agricultural water resources management with respect to fuzzy return and energy constraint under uncertainty: An integrated optimization approach

In this study, an integrated framework is proposed for agricultural water and land resources management under uncertain circumstances and energy-water nexus. The framework has two components: the optimized interval solutions generation of unknown market quotation and environment situation through the novel interval fuzzy-expectation programming, and the post-optimization decision-making of the tradeoff between system risk and return through risk-explicit interval programming. An optimization model based on the framework was developed from a real description for agricultural water resources system of Guangdong province under considering various crop, multiple water sources, and the related energy consumption in irrigation and drainage. The impact of energy consumption and risk level control on water resources allocation among different crops and system benefits were analyzed. The results indicated that the preference for surface water resources as the main water sources can effectively reduce regional irrigation energy consumption, and the planting area of each crop would have different variations duo to resources endowment constraints. Risk tradeoff-based results can provide valuable information and additional concern for developing low carbon-oriented agricultural water resources management schemes.

Physico-Chemistry of Surface Water Impacted by Crude Oil Spills in Bodo/Bonny Rivers, Nigeria

The surface water resources of Bodo/Bonny communities in Rivers State suffers regular pollution of its ecosystem due to increase in crude oil exploration, refining and activities of other industrial establishments operating within the coastal areas of the Ogoniland of the Niger Delta region of Nigeria. This have resulted in the wide scale contamination of most of its creeks, swamps and rivers with hydrocarbons and dispersant products resulting in the alteration of the ecological integrity of fragile aquatic systems, bioaccumulation of chemical contaminants by zoobenthos, sediment enrichment, and smothering or asphyxiation of the organisms in water by oil coating, thereby causing death. These conditions have resulted in serious threat to public health and the ecosystems. The study was aimed at determining the physico-chemical characteristics of Bodo/Bonny coastal waters impacted by crude oil spills and their effect on the marine ecosystems. Surface water was collected from 5 stations (BBW1, BBW2, BBW3, BBW4 and LFPW5) with LFPW5 serving as control. Physico-chemical parameters were investigated following standard methods. The results of the physicochemical characteristics of the various sampling points in the dry season showed that pH, TDS and Electrical conductivity values showed statistically significant differences at P < 0.005. pH was slightly acidic in all sampling locations except for the Link fish pond, the values ranged from 6.20–6.40 which was below DPR Limit of 6.5-8.5 for potable water, TDS recorded 43175–57075 mg/L above DPR permissible Limit of 5000mg/L. Electrical Conductivity (EC) values ranged from 54050 -57050 µS/cm. The Dissolved Oxygen, Biological Oxygen Demand, Turbidity, Chloride recorded in this study varied significantly at P< 0.05. Results of the physicochemical parameters of surface water in the wet season fell within the standard limits except for the conductivity that was above the permissible limits. Comparatively the mean pH value of surface river water with Linked fish pond water which served as the control revealed that the Link fish pond water had the highest pH value of 7.9 than the surface river water samples with a pH of 6.4, TDS (60,200 mg/L), Electrical Conductivity (EC) (µS/cm3) followed a similar pattern with the mean EC value of 55,800 mg/L as against 750mg/L for the Link Fish pond water. Temperature recorded 310C as against 300C for the link fish pond while the Salinity (mg/L) of the surface river water was 31.63 mg/L. Dissolved Oxygen was 2.3 mg/L, Biochemical Oxygen Demand values for the surface river water was 0.49 mg/L while the Link fish pond water had 0.3mg/L. These values obtained in this study shows that the spilled oil in the water could impact on species abundance and biomass by depleting and depriving the fishes from available O2 for survival thus resulting in asphyxiation.

Water quality characteristics and health risk assessment of main water supply reservoirs in Taizhou City, East China

Taizhou is a typical coastal area in East China where drinking water is mainly supplied by reservoir water. The water quality of the reservoirs may be affected to some extent by human activities and climate. Therefore, the purpose of this study is to evaluate the water quality characteristics of the main water supply reservoirs in Taizhou City, Zhejiang Province, and to study the influence of the two rainy periods, the plum rains period and the typhoon rains period, on the water quality of the reservoirs using the entropy water quality index evaluation method. Total non-carcinogenic and carcinogenic health risks from different exposure pathways were assessed for people at different ages. It is found that the water quality of the main water supply reservoirs in Taizhou City is generally good and suitable for drinking, but the water quality of the reservoirs will deteriorate during the rainy seasons. Non-carcinogenic health risks are at acceptable levels for all age groups, but unacceptable high carcinogenic health risks are observed for both children and adults, which is mainly caused by As. Through this study, local decision-makers can be better informed for a better management of surface water resources in this area.

Assessment of Water Quality Index and Pollution Load Capacity in the Sukowidi River and Bendo River, Banyuwangi Region

The river is a part of the surface water resource which is very potential for living. The quality of river water is greatly influenced by land use and human activities in the catchment area. Increasing the number population in Banyuwangi Region and its activity has the potential to reduce the water quality of the river, especially in the Sukowidi and Bendo catchment area, therefore it is necessary to assess the water quality. This research was conducted to identify the source of pollutants and determine the pollution index, status of water pollution, as well as to determine pollution load capacity. The data analysis was carried out quantitatively and graphically, and spatially with the QUAL2Kw and the Inverse Distance Weighted (IDW) by using ArcGIS 10.4.1. Land use on the two rivers is slightly different, that is rural, suburban, and urban areas. The pollution sources in the study area were point source and non-point source. The results showed that the pollution status of the Sukowidi River was "Light Polluted" and the high pollutant load carrying capacity had total suspended solids and nitrates. Meanwhile, in the Bendo River, the pollution status is not polluted yet and the pollutant load carrying capacity is on the quality standards. These findings provide valuable information and guidance for the Banyuwangi Regency government to decide on land use policy.

National Stable Isotope Baseline for Precipitation in Malawi to Underpin Integrated Water Resources Management

With the resurgence of water-isotope tracing applications for Integrated Water Resource Management in developing countries, establishing a stable isotopic baseline is necessary. Developing countries, including Malawi, continue to struggle with the generation of consistent and long-term isotopic datasets due to non-existent or inadequate in-country water-isotope capacity. Malawi has made significant advances in its quest to establish a stable isotopic baseline through the establishment of the Malawi Network of Isotope in Precipitation. This study provides the first results for the isotopic characterization of precipitation in Malawi with a view to reinforcing understanding of the country’s hydrological cycle. Error-in-variables regression defined a Local Meteoric Water Line as δ2H = 8.0 (±0.3) δ18O + 13.0 (±2.0) using stable isotopic records of 37 monthly samples from 5 stations between 2014 and 2019. Local precipitation (isotopic composition) is consistent with global precipitation expectations, its condensation-forming process occurring under equilibrium conditions and a higher intercept (d-excess) above the 10‰ for Global Meteoric Water Line, implying that air moisture recycling significantly influences local precipitation. Wider variations observed in local precipitation isotopic signatures are largely attributed to different moisture-bearing systems and diverse geographic factors across the country. Additional stations are recommended to improve spatial coverage that, together with longer temporal records, may help understanding and resolving uncertainties such as the altitude effect. This pioneering study is expected to facilitate Malawi’s ambition to achieve integrated use and improved protection of its surface water and groundwater resources in response to mounting climate change, growing population and land-development concerns.

Quality Assessment of Surface Water for Domestic and Agricultural Purposes Using Hydro-chemical and Microbial Studies in Kilifi County, North Coast Region of Kenya

Water has economic and ecological significance. However, quality deterioration due to salinity causes significant decrease in agricultural productivity and a public health problem. This study focuses on hydro-chemical and microbial quality of water sources in Kilifi County. Water samples were collected from 25 different locations within Kilifi County and indicators of salinity and microbial load analyzed. Temperature, pH, EC and TDS were determined using portable pH meter. Anions; F-, Br-, Cl-, SO42-, PO43-, NO2-, NO3-, CO32-, HCO3- and NH4+ were determined using Ion Exchange Chromatography. Cations; Na+, K+, Ca2+, Mg2+, Zn2+, Fe2+, Cd2+, Cr3+, Al3+ and Ag+ were determined using flame photometry. Standard methods were used to determine Microbial loads. Results were pH (7.42±0.52), Temperature (24.61±0.21oC), EC (3.44±0.75 dscm-1), TDS (1672.53±122.87 mgL-1) and Turbidity (152.29±41.20 NTU). Anions; F- (2.90±0.24 mg/L), Cl- (1756.68±900.50 mg/L), NO2- (4.47±0.49 mg/L), Br- (11.72±1.20 mg/L), NO3- (4.67±0.38 mg/L), HCO3- (200.54±25.58 mg/L) PO43- (0.94±0.10 mg/L), CO32- (29.94±2.32 mg/L), and SO42- (300.64±42.47 mg/L). Cations; K+ (8751.80±214.04 mgL-1), Na+ (59.43±1.98 mgL-1), Ca2+ (4.00±0.16 mgL-1), Mg2+ (59.43±1.98 mgL-1), Zn2+ (0.76±0.30 mgL-1), Cu2+ (0.18±0.01 mgL-1), Ag+ (0.03±0.01 mg/L), Cd2+ (0.07±0.01 mg/L), Cr3+ (0.35±0.01 mg/L), Al3+ (0.33±0.01 mg/L) and NH4+ (2.01±1.96 mg/L). Microbial load; MPN (20811.00±402.00), Total coliforms (2970.00±60.00 CFU 100 mL-1), E. coli (26.00±3.00 CFU 100mL-1), S. aureus (411.00±12.00 CFU 100mL-1), Shegela (24.00±2.00 CFU 100mL-1) and S. typhi (67.00±2.00 CFU 100mL-1). Temperature, pH, EC, TDS, Turbidity, F-, Cl-, Br-, PO43-, Na+, Zn2+, Fe2+ and microbial load were above WHO limits whereas SO42-, NO2-, NO3-, CO32-, HCO3-, NH4+, K+, Ca2+, Mg2+, Cd2+, Cr3+, Al3+ and Ag+ were below WHO limits. The study concludes that water sources in Kilifi County are unsuitable for domestic and agricultural uses. It’s recommended that a continuous water quality monitoring program be put in place and development of effective management practices for utilization of the surface water resources be instituted.