Water circulation in karst systems: comparing physicochemical and environmental isotopic data interpretation

Asante, Joseph; Dotson, Sam; Hart, Evan A.; Kreamer, David K.

doi:10.1007/s12665-018-7596-y

Cited by 7 publications

(2 citation statements)

References 33 publications

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“…The Five water conversion process water in a typical epikarst zone is synchronous and non-independent (Luo et al, 2003;Joseph et al, 2018). The process of precipitation in converting into overland ow, soil water, and groundwater occurs synchronously with the process of conversion of soil water and ssure water into groundwater, vegetation roots drawing water from the soil for transpiration, and surface evaporation.…”

Section: Comprehensive Analysis Of Five Water Transformation Processmentioning

confidence: 99%

Transformation Process of Five Water in Epikarst Zone: A Case Study in Subtropical Karst Area

Song¹,

Zhang²,

Liu³

et al. 2021

Preprint

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Five water stand for five forms existence models of water. In Karst area, Five water means precipitation, groundwater, evapotranspiration water, soil water, and overland flow. The complicated water-bearing hydrogeological media and the inhomogeneous water storage structure leads to low efficiency of water utilization. To reveal intricated water resources transformation in karst areas, a typical epikarst zone was selected. The Five water and their conversion processes were studied and the transformation models was built based on the long-term positioning observations. The results show that: (1) Overland flow can be generated when precipitation reaches 6 mm and lasts for 6 h. Under light and moderate rainfall (LMR) conditions, less than 6% of the precipitation is converted to overland flow. Under heavy rainfall and rainstorm (HRR) conditions, the conversion rate is 3.5%-6%. (2) Under the condition of LMR, there are 2%-3.5%, 40%-60% and 25%-35% that transformed to vegetation water, soil water and groundwater respectively, while it is 1.5%-2.2%, 25%-30% and 32%-50% under the condition of HRR. (3) The proportion of precipitation was transformed to soil water is 20%-70%. (4) The conversion rate of groundwater and karst fissure water for LMR conditions are 8%-15% and 10%-15%, and that for HRR is 15%- 20% and 20%-35%. (5) The proportions of different degrees of precipitation transformed into vegetation transpiration and evaporation water are 1.5%-3.5% and 6%-9%, respectively. (6) Generally, about 0%-4% of the precipitation is converted into overland flow, 20%-70% into soil water, 25%-50% into karst groundwater, and 1%-10% into evaporative water.

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Section: Comprehensive Analysis Of Five Water Transformation Processmentioning

confidence: 99%

Transformation Process of Five Water in Epikarst Zone: A Case Study in Subtropical Karst Area

Song¹,

Zhang²,

Liu³

et al. 2021

Preprint

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“…Due to its unique climatic conditions and long-term karstification, soil layer in the study area is extremely thin and the rate of soil formation is slow (Gong et al 2012). Moreover, soil thickness in the study area is highly heterogeneous (Zhang et al 2014;Asante et al 2018). Soil thickness is an important index in soil degradation research and in assessments of land productivity.…”

Section: Introductionmentioning

confidence: 99%

Driving forest succession in karst areas of Chongqing municipality over the past decade

Xiao

Liu

et al. 2020

For. Ecosyst.

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Background: Karst areas in southwestern China exhibit ecological degradation in the form of rocky desertification. Local governments launched large-scale afforestation and other ecological restoration programs to curb this trend. Soil thickness is a key limiting factor for vegetation restoration in Karst areas, but the relationship between ecological restoration and soil thickness remains unclear. Further, afforestation consumes large amounts of water, which impacts water supply in karst areas. In this study, we used GIS and statistical analyses to determine rocky desertification sensitivity and its driving factors in karst areas of Chongqing municipality over the past decade. Results: Soil thickness is one of the key factors that restrict ecological restoration of rocky desertification. From 2000 to 2010, rocky desertification sensitivity in karst areas was on the rise along with an increase in afforestation. Areas of high sensitivity were mainly distributed in Pengshui County, Wulong District, and Youyang County; Shizhu County had the lowest overall incidence of desertification. Spatial distribution of rocky desertification was significantly affected by rainfall and soil thickness. Regression analysis showed that the main factors controlling changes in rocky desertification in natural forest over time were precipitation which explained 23.73% of total variance, and soil thickness which explained 23.42% of total variance. Soil thickness and soil water content had a higher correlation coefficient (at 0.516) in natural forests than in planted forests. Conclusion: This study showed that increases in soil thickness in a karst area had a significant positive impact on the fragile ecological environment. This indicates that ecosystem restoration in karst areas will benefit from addressing soil thickness.

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Fate of nitrate during groundwater recharge in a fractured karst aquifer in Southwest Germany

et al. 2021

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Over the past decades, fractured and karst groundwater systems have been studied intensively due to their high vulnerability to nitrate (NO3−) contamination, yet nitrogen (N) turnover processes within the recharge area are still poorly understood. This study investigated the role of the karstified recharge area in NO3− transfer and turnover by combining isotopic analysis of NO3− and nitrite (NO2−) with time series data of hydraulic heads and specific electrical conductivity from groundwater monitoring wells and a karstic spring in Germany. A large spatial variability of groundwater NO3− concentrations (0.1–0.8 mM) was observed, which cannot be explained solely by agricultural land use. Natural-abundance N and O isotope measurements of NO3− (δ15N and δ18O) confirm that NO3− derives mainly from manure or fertilizer applications. Fractional N elimination by denitrification is indicated by relatively high δ15N- and δ18O-NO3− values, elevated NO2− concentrations (0.05–0.14 mM), and δ15N-NO2− values that were systematically lower than the corresponding values of δ15N-NO3−. Hydraulic and chemical response patterns of groundwater wells suggest that rain events result in the displacement of water from transient storage compartments such as the epikarst or the fissure network of the phreatic zone. Although O2 levels of the investigated groundwaters were close to saturation, local denitrification might be promoted in microoxic or anoxic niches formed in the ferrous iron-bearing carbonate rock formations. The results revealed that (temporarily) saturated fissure networks in the phreatic zone and the epikarst may play an important role in N turnover during the recharge of fractured aquifers.

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Water circulation in karst systems: comparing physicochemical and environmental isotopic data interpretation

Cited by 7 publications

References 33 publications

Transformation Process of Five Water in Epikarst Zone: A Case Study in Subtropical Karst Area

Transformation Process of Five Water in Epikarst Zone: A Case Study in Subtropical Karst Area

Driving forest succession in karst areas of Chongqing municipality over the past decade

Fate of nitrate during groundwater recharge in a fractured karst aquifer in Southwest Germany

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