Watershed Resources Research Articles

Determinants of Public Participation in Watershed Management in Southeast China: An Application of the Institutional Analysis and Development Framework

Increasingly, adaptive processes and decentralization are vital aspects of watershed governance. Equitable and sustainable water governance requires an understanding that different societal members have unique relationships with the environment and varying levels of interaction with policymakers. However, the factors facilitating public involvement under centralized governance remain less understood. This study combined the Institutional Analysis and Development framework with ordered probit regression to empirically investigate the determinants of willingness to participate (WTP) and actual participation of the public in integrated watershed management (IWM). Data from 933 valid questionnaires collected across 36 counties in Fujian, China, were used to define stakeholders’ perceptions of IWM. Results show that stakeholders are predominantly willing to participate in watershed conservation, management, or planning (85.9%), while only 32.8% frequently attend related events. Pro-environmental intentions were mainly shaped by interactional capacity—information exposure, interpersonal exchanges, and cross-reach support recognition—while actual participation was influenced by perceived biophysical conditions, rules-in-use, socioeconomic factors, and interactional capacity. Frequent observations of poor forest management practices were correlated with higher behavioral intentions, and socioeconomic dynamics significantly affected self-reported actual participation. Information sharing had the most substantial positive impact on both WTP and actual participation. These findings reinforce the necessity for an integrated and holistic approach to regional watershed resource management that fosters inclusivity and sustainability. This study provides workable insights into the social and institutional factors that shape public participation in watershed governance as it evolves toward decentralization.

Assessing Hydrological Response and Resilience of Watersheds as Strategy for Climatic Change Adaptation in Neotropical Region

This study aimed to assess the hydrological response and resilience of watersheds in a neotropical region to identify regions sensitive to climate variations, enabling the development of adaptive strategies in response to global environmental changes. This study applied Budyko’s framework using Fuh’s hydrological model rewritten by Zhou to estimate hydrological response and Budyko’s metrics (deviation and elasticity) to estimate hydrological resilience to climatic changes in 26 watersheds in southeastern Brazil. The proposed modeling was able to capture the differences among the watersheds, with “m” values ranging from 1.79 to 3.63. It was possible to rank the hydrological resilience from low to high across watersheds using Budyko’s metrics, where the highest values of elasticity were found in watersheds with a higher percentage of forest cover. The sensitive analyses showed that watersheds with higher “m” values are more sensitive to changes in precipitation and potential evapotranspiration. The results also demonstrate that mean elevation and stream density were two key variables that influence the “m” value; these physiographic characteristics may alter the water and energy balance of the watershed affecting the water yield. A relationship between watershed’s hydrological response and resilience was proposed to identify critical areas for the stability of water yield in the watersheds, providing a guide for public policy and suggesting ways to help the management of water resources in watersheds.

The Spatiotemporal Variation and Ecological Evaluation of Macroinvertebrate Functional Feeding Groups in the Upper Yellow River.

Against the backdrop of hydropower development in the upper Yellow River, comprehending the spatiotemporal variation and ecological evaluation of macroinvertebrate functional feeding groups (FFGs) is paramount for the conservation and restoration of aquatic biological resources in watersheds. Detailed surveys of macroinvertebrates were conducted in the gorge and plain areas of the upper Yellow River in July 2022 and March, May, and October 2023, culminating in the identification of 65 taxonomic units (genus or species) spanning 4 phyla, 14 orders, and 35 families. Of these, 41 taxonomic units were discovered in the gorge areas and 57 in the plain areas. Among the FFGs of macroinvertebrates in the upper Yellow River, collector-gatherers were overwhelmingly dominant, followed by scrapers, collector-filterers, predators, and shredders. Concerning river section types, dominant species in the gorge areas included Gammarus sp., Limnodrilus hoffmeisteri, and Polypedilum sp. among collector-gatherers, while in the plain areas, dominant species included Ecdyonurus sp. among scrapers, Hydropsyche sp. among collector-filterers, and Gammarus sp., Limnodrilus hoffmeisteri, and Chironomus sp. among collector-gatherers. A Mantel test revealed that dissolved oxygen, conductivity, and orthophosphate were the primary environmental factors affecting the FFGs of macroinvertebrates in the upper Yellow River, with variations observed in their effects across different months. The evaluation results of the Hilsenhoff Biological Index and Shannon-Wiener Index indicate that the water quality of the upper Yellow River is at a moderate level. An assessment of the upper Yellow River ecosystem using FFG parameters demonstrated that macroinvertebrate biomass progressively increased from upstream (gorge areas) to downstream (plain areas) spatially, accompanied by increasing habitat stability, with cascade hydropower development identified as a key factor impacting habitat stability. These findings provide pertinent data and a theoretical foundation for the protection of aquatic biological resources and watershed management in the upper Yellow River.

Comparative Assessment of Physicochemical and Biological Indicies of Otamiri and Nworie River Using a Piper Diagram Model

The Surface Water Resources of Otamiri-Nworie Watershed within the Owerri Metropolis were studied with the prime aim of developing a Non-Point Source Event-Based Model to Contamination of the water bodies. Clean, safe, and sufficient water is essential for both human existence and the health of ecosystems, communities, and economies (Fubara and Kpormon, 2023). As human populations increase, industrial and agricultural production increases, and climate change pose a threat of significant disruption of the hydrologic cycle, and as such, declining water quality has emerged as a major global problem (Ogbonna and Orinya, 2023). Human-drinking water must be free of organisms and chemical substances, as high amounts might be harmful to one’s health (Adeyi et al., 2021). This study aimed at comparatively assessing the physicochemical and biological indices of Otamiri and Nworie Rivers, and the Piper diagram model was employed for the analysis. Fifteen water samples were collected along the course of the two rivers and analyzed for physical, chemical and microbial parameters. Physical, chemical, and biological parameters were analyzed. The analytical results of the samples were compared with notable standards like the World Health Organization [WHO], etc. It was observed that all the parameters analyzed for the rivers fall below the acceptable standards except for pH (6.5-8.5) indicating the acidic nature of these water bodies. Similarly, the colour value of the two rivers ranges between 21.5 to 229 PCU and observed to be decreasing downstream within Nworie and Otamiri rivers. Within the river Nworie axis, both the total dissolved solids (TDS) and the total suspended solids (TSS) were observed to be increasing downstream. Along Otamiri river before confluence, total dissolved solids increased downstream whereas the reverse was the case for the total suspended solids, just after the confluence. There is a noticeable increase in dissolved oxygen (DO) downstream within the Nworie axis. The biological oxygen demand (BOD) values for the rivers were below the WHO standard. Finally, the major sources of contamination within the study area revealed that they are mainly from agricultural practices, dumpsites, and human defecation. The quality can be improved by applying appropriate treatment to the water before its use for various purposes.

Multi-criteria evaluation of the environmental carrying capacity (ECC) of Gharesou watershed in Ardabil province to optimal utilization of watershed resource

Multi-criteria evaluation of the environmental carrying capacity (ECC) of Gharesou watershed in Ardabil province to optimal utilization of watershed resource

Revitalizing Key Conditions and Integrated Watershed Management to Mitigate Land Degradation and Sustain Water Availability for Agriculture in Semi-Arid Regions: A Case Study of Ethiopia

Land, the source of 97% of global food, remains threatened by progressive soil erosion-induced land degradation, such as, in the semi-arid regions. To address this problem, soil and water conservation interventions have been implemented in watersheds across Ethiopia. Despite witnessing successful and positive impacts in some watersheds, the broader promotion of watershed-based interventions faces obstacles. Soil and water deteriorations persist in many of the watersheds in Ethiopia, leading to water shortages and related challenges in sustaining agriculture. The objectives of this research are thus to i) identify the main challenges and constraints hindering the promotion of watershed-based interventions in Ethiopia, and ii) identify key conditions for revitalizing the Integrated Watershed Management (IWSM) approach to mitigate soil erosion-induced land degradation, rehabilitate and sustainably manage watershed resources. A systematic review of over 60 published articles, extracted from the internet database using various search engines such as Google Scholar, ScienceDirect, Academia.edu, and ResearchGate, was conducted. Additionally, valuable comments from 65 peer-reviewers worldwide were collected through the Qeios platform during a posting period for more than two months, and these comments were utilized to update the first preprint version of this article. Based on the review, identified challenges and limitations include poor institutional support, lack of participation, inadequate planning of soil and water conservation (SWC) technologies, absence of research and development linkages, and insufficient capacity building. To address these challenges and limitations, recommendations for revitalizing the integrated watershed management (IWSM) approach and key conditions are discussed. The identified key conditions for revitalizing watershed-based interventions in Ethiopia include: i) ensuring institutional support and community participation, ii) strengthening the watershed-based intervention, and iii) establishing a watershed-based platform for scientific tools, research-based innovation, and capacity building to sustain water availability for agriculture in Ethiopia, serving as an experience for other semi-arid regions.

Use of Plantation Establishment and Livelihood Improvement Scheme (Pelis) in the Rehabilitation of Nyamweru Forest Reserve, Kiambu County, Kenya.

PELIS is a program globally known as the Taungya system, which involves the allocation of parcels of land to forest-adjacent communities to grow tree seedlings as well as carry out cultivation of crops during the early stages of tree seedlings growth until they form canopies, with the aim of increasing forest cover. The program has been successful in some countries, but it has failed in other countries, especially developing countries. This study investigated the impeding factors to the realization of the PELIS program, using a case study of the Nyamweru forest reserve in Kiambu County, Lari sub-county, Kenya. Descriptive research design was employed, with a sample size of 40 respondents. About 80% of the results showed an apparent weakness of the institutions mandated in the governance of the forest to effectively manage PELIS program. The study concluded that all the challenges experienced under the PELIS program can be linked to poor forest governance practices. The study recommended, that an integrated watershed resource management, adoption of a bottom-up approach in order to achieve participatory forest management in all aspects of the PELIS program, and development of a platform for awareness creation, such training and use of current technologies, to strengthen and enhance social capital in PELIS program Management in order to, rejuvenate and achieve the constitutional recommended 10% of forest cover in Kenya.

Synergistic roles of articulation, intellectual passion, conviviality and commitment in determining the citizens’ awareness and initiatives for sustainable watershed resources management

To attain high quality watershed, citizens or stakeholders should work harmoniously with the researchers and the local government units. There should be a pleasant relationship among the three which can only be attained if there is intellectual passion among the three concerned characters. This watershed management research has employed a combined socio-scientific and philosophical research design. The researchers as scientists are determined to be actively involved in sharing his intellectual passion to attain greater objectivity and rationality in sustaining watershed resources. This study found that people's jobs and social status significantly influenced their awareness and actions regarding watershed conservation. Students, local government officials, and local residents have only a moderate understanding of how industrialization impacts watershed resources. Surprisingly, local government officials are unaware of how siltation affects the quality and biodiversity of these resources. Additionally, students show little initiative in attending watershed conservation seminars, likely due to the high cost of scientific conferences, which they may find financially challenging. Through the inculcation of Polanyi’s philosophical concepts, the researchers highly recommend the conduct of more hands-on community outreach activities regarding watershed conservation.

Priorización de cuencas hidrográficas para la conservación del suelo y el agua basado en las técnicas GIS, PCA y WSA

Soil and water conservation is a priority in the watersheds of arid and semi-arid regions for the proper planning and integrated management of water resources. The objective of this work is prioritizing 91 watersheds in 14 regions of Peru with different geographical, hydrological and geological conditions, through the integration of Geographic Information Systems (GIS), Principal Component Analysis (PCA) and the Weighted Sum Approach (WSA). In addition, homogeneous regions were identified with hierarchical Cluster Analysis in R and Ward's method. The result showed the existence of 19.49 % of total area in high and very high priority category in two regions. The results of the Cluster Analysis showed that 35 % of the watersheds have homogeneous zones within the geometric and shape factor, while 65 % within the drainage and relief factor. In general, GIS, PCA and SWA methods are an efficient tool, which allows decision-making authorities for better planning and conservation of natural resources in hydrographic watersheds.

Analysis Of The Spatial And Temporal Variability Of Rainfall In The Kayanga-Anambé Hydrological Complex (Republic Of Guinea And Senegal)

The high rainfall variability observed especially from the 1970s has intensified the vulnerability of water resources in tropical watersheds. It resulted in the recurrence of extreme hydrological events – combined with the increase in temperature which increases evapotranspiration causing considerable water losses – but also in the "Sahelization" of Sudanian areas resulting in the migration of isohyets towards the south.This article studies recent spatial and temporal changes in rainfall in the Kayanga-Anambé complex, as well as their potential hydrological implications. The methodological approach is based on (i) checking the quality of data and filling gaps using the method of rainfall indices with the Regional Vector Method (RVM); and on (ii) the analysis of spatial and temporal variability of rainfall using PETITT stationarity test and Standardized Precipitation Index (SPI).The evolution of rainfall in the basin is reflected in a fact specific to the intertropical zone, namely the variability of rainfall. This is marked by several sequences: a wet period between 1940 and 1967, followed by a long dry sequence which extends between the beginning of the 70s until the end of the 90s, and finally a slight resumption of the rainfall over the period 1993-2020. However, according to the outputs of global climate models ("Multi-model Ensemble"), the resumption of rainfall in the Kayanga basin will only be effective from 2060. This variability noted in the rains will induce a similar variability in the flows and agricultural production since they are largely dependent on it.

An integrated framework for improving watershed management planning

Proper land use and management (LUM) planning is pivotal to curbing land degradation and ensuring sustainable use of limited watershed resources. Despite decades of research and development efforts, land degradation remains a serious environmental problem in many parts of the world. Issues regarding the sustainability of current LUM initiatives are due to poor linkages between the ecological and socio-economic dimensions of LUM decisions, and an integrated framework allowing LUM interventions to be properly planned and implemented is lacking. In this study, we developed an integrated framework to identify, evaluate, and propose LUM alternatives with ecological and socio-economic benefits. The framework comprises six components: (i) identification of land use problems and setting of objectives, (ii) identification of the best-performing land use-based integrated solutions, (iii) formulation of LUM alternatives and modeling of key indicators, (iv) cost-benefit analysis, (v) evaluation of the LUM alternatives with stakeholders engagement, and (vi) communication of the LUM alternatives to relevant stakeholders to obtain institutional and financial support for implementation. To demonstrate the use of this framework, we conducted a case study in the Aba Gerima watershed of the Upper Blue Nile basin in Ethiopia. This study used extensive plot- and watershed-scale observations (2015–2019) obtained under both conventional and improved sustainable land management practices. We analyzed changes in runoff, soil loss, soil organic carbon (SOC) stock, and land productivity of five LUM alternatives as compared to a baseline scenario (existing farming practices). The results showed that the LUM alternatives reduced runoff by 11–71% and soil loss by 66–95%, and SOC stock and watershed-scale land productivity were improved by 36–104% and 48–134%, respectively. Evaluation of LUM alternatives by stakeholders, including land users, policy makers, and researchers, produced divergent results. In particular, land users prioritized implementation of sustainable land management practices without altering existing land uses. The integrated framework developed in this study can serve as a valuable tool for identifying, evaluating, and proposing LUM alternatives and facilitating decision-making in planning and implementation of LUM practices in watersheds experiencing land degradation.

MAP ANALYSIS OF LAND USE IN KHILAU SUB-SUB WATERSHED, WAY BULOK SUB-WATERSHED, WAY SEKAMPUNG WATERSHED, LAMPUNG PROVINCE

An increase in population impacts conditions of forest, soil, and water resources in watersheds through land use change. One of the hydrological components in the watershed influenced by this change is the surface flow coefficient (C). This study aimed to analyze the land characteristics of the Khilau Sub-Sub Watershed, Bulok Sub-Watershed, Sekampung Watershed, Lampung Province. The research methods involved taking aerial photos and field observation with an application called ArcView GIS MAP as the research tool. The analysis results signify that the land use in the watershed was divided into 6 main types with a total area of 671.6776 Ha. The surface flow coefficient value (Ctotal) was 0.1412, which indicates that all rainwater falling into the watershed was well infiltrated into the soil so that the land use was categorized as good. It was found out that, with the use of the GIS application, the land use in the Khilau Sub-Sub Watershed comprises 6 main types, i.e. mixed gardens, forests, annuals, shrubs, settlements, and rice fields. The mixed garden type of land use has the highest coefficient (C) value of surface flow runoff, so it Therefore, the rainwater in the watershed area is well infiltrated into the soil so that it is safe to categorize the land use as good.

Paleohydrologic history of pluvial lake San Agustin, New Mexico: Tracking changing effective moisture in southwest North America through the last glacial transition

Paleoclimate records across the Intermountain West region of North America show significant regional variation in timing and magnitude of wet conditions that accompanied the last glacial-interglacial transition. To understand the climate controls on paleohydrologic change, well-dated records are needed across the region. The Plains of San Agustin (New Mexico, USA) is a closed-basin watershed of the American Southwest influenced by both winter westerly and summer North American Monsoon precipitation. The flat valley floors of the Plains contain lake and groundwater discharge deposits that record multiple periods of past wet climate. We present a record of hydroclimate for the past 26,000 years based on radiocarbon, U–Th series, and OSL dating of these deposits and stratigraphic correlation across the three sub-basins of the lake system. We find that two major lake oscillations occurred, coincident with the global Last Glacial Maximum (∼23–18 ka) and with Heinrich Stadial 1 (∼17–14 ka). The LGM lake cycle created a deep lake in the lowermost sub-basin, fed by marsh/lake overflow in the upper sub-basins. The Heinrich Stadial 1 wet interval attained the highest recorded lake level between ∼17.0 and 15.3 ka, merging the lower two sub-basins into one lake. Both lake cycles agree well in timing and magnitude with other lake-based records from the southwestern U.S., supporting previous interpretations that a south-shifted cool season storm track brought a dipole-like pattern of enhanced moisture to the southwest at the expense of drier conditions in the northwest during the LGM and deglaciation. A transition from lake to groundwater discharge conditions followed during the Bølling-Allerød (14.7–12.9 ka) across the study area. Wet meadows prevailed in the lower sub-basin during the Younger Dryas (12.9–11.7 ka), with marsh and open lake conditions in the upper and middle sub-basins, respectively. During the early Holocene, discrete wet intervals are recorded by ages for wet meadow deposits in all sub-basins with centennial-millennial frequency at 9.9, 8.8, 8.2 ka. These events agree well with other Intermountain West records showing wetter-than-present conditions prior to 8 ka. Two additional wet periods, centered at 6.8 and 5.4 ka, occurred during the driest known interval of the middle Holocene, and likely were partly supported in the Plains of San Agustin by summer moisture associated with the peak strength of the North American Monsoon. Our record highlights that both winter and summer moisture support water resources in New Mexico watersheds.

Microbial contamination effects on the hydrochemical parameter in a Thettiyar watershed, Kerala, India, using GIS.

The present study has been carried out to assess the quality of groundwater and surface water resources of Thettiyar watershed, Kerala, India. Sixty-six water samples were collected during pre-monsoon (April, 2019) and monsoon (July, 2019) season, and analyzed for pH, electrical conductivity (EC), total dissolved solids (TDS), total hardness and major cations and anions and microbiological parameters as well. According to the piper diagram's plot, Ca and Mg dominate over Na among the cations, and Cl is the most prevalent anion in groundwater throughout both the studied seasons. The hydrochemical analysis of water samples revealed that all the parameters are within the permissible limit except for pH. For microbiological analysis, the samples were tested for total coliform and fecal coliform. Most of the groundwater samples collected have higher total coliform and fecal coliform (E. coli) content than the recommended count by BIS (2012). The pre-monsoon surface water samples owned a maximum number of 3700cfu/100ml (TNTC-too numerous to count) of total coliform and 1400cfu/100ml (TNTC) of fecal coliform. In monsoon, the number of total coliform and fecal coliform has increased to 3800cfu/100ml and 1900cfu/100ml respectively. E. coli and total coliform are effectively correlated with each other in both seasons, in accordance with the statistical study. Domestic, sewage dump, and other household wastes are the main sources of bacterial contamination in the study area, which in turn nourishes contaminant organisms. According to the results, the government or municipality should implement an appropriate system for managing solid waste and should take all necessary measures to clean up the study area.

Land Use and Land Cover Change Analysis Using Google Earth Engine in Manamati Watershed of Kathmandu District, Nepal

Understanding the changes in land use and land cover (LULC) is essential in managing and monitoring the resources and planning. This study has analyzed the LULC changes in the years between 1992 and 2017 in Manamati watershed, Kathmandu district. Google Earth Engine Java Script API has been used to prepare LULC database. The supervised classification of a maximum likelihood algorithm is also used to prepare LULC database. The result shows that more than 6% land of the cultivated area has been converted into built-up area from 1992 to 2017, and 2.43 km2 area has increased in built-up area. The forest-covered area seems to be constant, and it is not a significant change over the last 25 years. However, proper watershed management practice and land use planning require to control the threats to watershed resources. The results of this study could be a reference to the future planning of watershed resource management.

Identifying the Multi-Scale Influences of Climate Factors on Runoff Changes in a Typical Karst Watershed Using Wavelet Analysis

Identifying the impacts of climatic factors on runoff change has become a central topic in climate and hydrology research. This issue, however, has received minimal attention in karst watersheds worldwide. Multi-resolution analysis (MRA), continuous wavelet transform (CWT), cross wavelet transform (XWT) and wavelet transform coherence (WTC) are used to study the teleconnection in time and frequency between climate change and hydrological processes in a typical karst watershed at different time scales. The main results are: (1) All climatic factors exhibit a main cycle at 12-month time scales with runoff changes, but the main periodic bandwidth of rainfall on runoff changes is much wider than that of temperature and evaporation, indicating that rainfall is the main factor affecting runoff changes. (2) In other cycles, the impact of rainfall on runoff changes is the interlacing phenomena with positive and negative, but the impact of temperature and evaporation on runoff change is mainly negative. (3) The response of runoff to rainfall is in time in the high-energy region and the low-energy significant-correlation region and has shown a positive correlation with a smaller phase angle, but it is slightly lagged at 16-month time scales. Moreover, the runoff change lags behind temperature and evaporation for 1–2 months in those regions. (4) It has been found that there is a strong effect of rainfall over runoff, but a lesser effect of temperature and evaporation over runoff. The study sheds light on the main teleconnections between rainfall, evapotranspiration and surface runoff, which in turn might help to attain the better management of water resources in typical karst watersheds.

The Analysis Morphometric Watershed Dolabafra Baisn

Watershed of Dolabfra is one of the branches of little river in Pishder sub-district, this river flows down into The little river in almost three km far away from south of west of Sultanade village, this basic of river is located in latitude (northern Longitude °36: ¯25:꓿00-°36: ¯29: ꓿00.) (°45: ¯03: ꓿00- east °45: ¯13: ꓿00)eastern longitudes. the main resources of watershed is located the land of Kurdistan Region and board of Pishder sub-district, the source of water providing of this river is situated in a valley of Sharueta village. The main aim of this research includes two parts, the first one is recognition of the characteristics of environments of the area of the research and the second one is to design a special map for each one. Thus, for the purpose of analyzing and using the water resources in the area of the research. In the beginning analysis has been presented for the natural environment of the Basin of Dolabfre and its influence on system of the irrigation, such as (geology, topography, weather and soil) thus, this is through analyzing each of the natural characteristics and direct and indirect effect on flowing river. In the second part, the most important morphometric measures for basin has been carried out, in a way that there is a focus on characteristics of the research (square of the area, shape, height and low, net of the flow of the river). The outcome of the research reveals that natural characteristics of the area of research play main role in the richness of water resources and speed of flow of steam, brook and main river of the basin.

Research on Water-Level Recognition Method Based on Image Processing and Convolutional Neural Networks

Water level dynamics in catchment-scale rivers is an important factor for surface water studies. Manual measurement is highly accurate but inefficient. Using automatic water level sensors has disadvantages such as high cost and difficult maintenance. In this study, a water level recognition method based on digital image processing technology and CNN is proposed. For achieving batch segmentation of source images, the coordinates of the water ruler region in the source image and characters’ region and the scale lines’ region on the ruler are obtained by using image processing algorithms such as grayscale processing, edge detection, and the tilt correction method based on Hough-transform and morphological operations. The CNN is then used to identify the value of digital characters. Finally, the water level value is calculated according to the mathematical relationship between the number of scale lines detected by pixel traversal in the binarized image and the value of digital characters. This method is used to identify the water levels of the water ruler images collected in the Hulu watershed of the Qilian Mountains in Northwest China. The results show that the accuracy compared with the actual measured water level reached 94.6% and improved nearly 24% compared to the template matching algorithm. With high accuracy, low cost, and easy deployment and maintenance, this method can be applied to water level monitoring in mountainous rivers, providing an effective tool for watershed hydrology research and water resources management.

The Ajuricaba Basin Creek chemical signature of water resources: Geological sources and anthropogenic contributions

The Ajuricaba Basin Creek is located west of the Parana State, it is part of the Parana 3 Hydrographic Basin and it is located at southwest of the Marechal Candido Rondon county. Its area of around 18 km2 is manly used for agricultural purposes. The basin is part of the Serra Geral Aquifer System (SGAS), which comprises basic volcanic rocks of the Serra Geral Group. The main objectives of this study are the characterization of the hydrogeochemical environments and the understanding of the dissolved elements sources, both geological and human, in order to create a water circulation model of the basin. Two field campaigns, in August and November 2019, were done to collect water samples from surface waters (SW), phreatic aquifer (PA) and fractured aquifer (FA). During the 2019 field campaigns, the temperature, pH, total dissolved solids (TDS) and electrical conductivity (EC) were measured on site. Physicochemical parameters (SiO2, HCO3−, CO3−2, Cl−, F−, PO4−3, SO4−2, NO3−, NO2−, Ca+2, Mg+2, Na+, K+, Fe total, Mn+2, Nb, S, V, Zn, Al, Sr, Ba, P, Ti) of the collected samples were analysed. Preexisting data from December 2010 was also used to observe historical changes in water quality through time. Based on this data, statistical (univariate and correlation) and hydrochemical analysis were conducted in order to characterize the hydrogeochemical environments and surface and groundwater flows in the basin. Historical analysis revealed that SW and PA samples have the most significant impacts on water quality with double the median concentration of NO3− and three to nine times the concentration of Cl−. Hydrochemical analysis showed that SW have higher concentrations of HCO3−, Cl−, NO3−, Ca+2, Mg+2, Al, Sr, Ba and Fe, high TDS and neutral to acid pH. PA has the lowest TDS and acid pH and its main ions are HCO3−, NO3−, Ca+2 and Mg+2. In addition, FA was divided in: FA (Ca+2) with HCO3−, Ca+2 and Mg+2 as main ions, neutral pH and low TDS and FA (Na+) with CO3−2, HCO3−, SO4−2, Na+, V, Nb and P as main ions, basic pH and high TDS. SW has a similar pattern to PA and FA (Ca+2) indicating that the rivers are discharge zones for both aquifers. FA (Ca+2) has a similar hydrochemical signature to SGAS, confirming it origins. In opposition, the FA (Na+) aquifer hydrochemical signature differs from the SGAS and, in fact, is more similar to the one of the confined Guarani Aquifer System (GAS), suggesting a higher residence time. Fa (Na+) waters have higher TDS and basic pH, indicating a higher residence time and depth associated with the ascension of even deeper flows from GAS towards the basin. In addition to the hydrochemical model, this research also highlights the potential of the multielement-hydrochemistry to understand the relations between surface and groundwater resources contributing for the management of water resources in watersheds.

Hydrogeochemistry and Isotope Hydrology of Surface Water and Groundwater in the Mountain Watersheds of Daqing River, North China

Surface water and groundwater interaction variations in time and space are crucial for effective water management, especially in low-precipitation regions. To comprehensively determine the hydrochemical characteristics and interaction processes of surface water and groundwater and to investigate the decreasing causes of water resources in semi-arid mountainous watersheds under changing environments, intensive field surveys were conducted in the Daqing River watershed, a tributary of the Haihe River basin in northern China, during two different times of the year: after the rainy season (September 2018) and before the rainy season (July 2019). Sixty surface water and groundwater samples were collected along the mountainous watershed. Using a combination method of hydrogen and oxygen stable isotope tracing and hydrochemical analysis, the hydrogen and oxygen isotopes and hydrochemical characteristics of surface water and groundwater in the mountainous watershed of the Daqing River were analyzed. Furthermore, the effect of elevation (altitude) on isotopes was discussed, and the correlation between hydrogen and oxygen isotope composition and hydrochemical characteristics was obtained. The results were processed using endmember mixing analysis to determine the amount of contribution of the surface water and groundwater interaction processes. The results show that the hydrochemical characteristics are relatively stable in the mountainous watersheds of the Daqing River, and the surface water and groundwater are mainly of the HCO3-Ca type. The slope of the local meteoric water line is smaller than the slope of the global meteoric water line, and the δD and δ18O in surface water and groundwater show a good linear relationship both before and after the rainy season. There is a decreasing trend of the value of δ18O in surface water samples with decreasing altitude, but a decreasing trend of the value of δ18O in groundwater samples is not obvious. The evaporation intensity of surface water is stronger after the rainy season than before the rainy season, and the connection between the surface water and the groundwater is stronger before the rainy season. Influenced by topographic conditions and other factors, the exchange of surface water and groundwater is frequent, and there is a large difference in the exchange ratio before and after the rainy season. The exchange ratio can be more than 50% after the rainy season. Thus, the reasons for decreasing water resources in the mountains can be implied to be due to the increasing hydraulic gradient between the mountains and the piedmont plains, and the water resources are discharged more in the form of groundwater to the downstream. The conclusions help to enhance the understanding of the water cycle in the mountainous watershed and can provide some theoretical basis for the sustainable development and utilization of water resources in the Haihe River basin and the regional water ecology of the Xiong’an New Area.