Vulnerability assessment is one of the most effective tools for the quality protection of karst aquifers. In the COP method, three essential factors, i.e., karstification process (K), atmospheric ...conditions (A), and tectonic (T) of the KARSTLOP method, are not considered despite being important factors in karstic aquifer vulnerability. This study aims to develop a new method to obtain the vulnerability map for karst aquifers based on the COP method and the factors used in the KARSTLOP method. The new method, namely COP*KAT, considers K, A, and T factors in the COP method using fuzzy logic. A comparison of microbial and nitrate contamination indices for livestock and agriculture land use, respectively, to the distribution of vulnerability classes for three springs in the study area (Dorfak region, Iran) reveals the more efficient performance of COP*KAT compared to COP in vulnerability analysis.
Determination of recharge from precipitation and its distribution in karst areas is of great importance in water budget calculations. Several multi-parameter weighting-rating methods have been ...proposed to determine the recharge into karst aquifers; one of the most precise methods used in this field is the KARSTLOP. It is always necessary that the weight of recharge estimation method becomes calibrated by new techniques due to the diversity conditions of each area. Therefore, in this study, the analytical hierarchy process (AHP) technique has been used as a powerful decision-helping subjective tool. Using this method, the weights of the original KARSTLOP method were modified and improved based on the comments from water experts in the area. The mean annual recharge in the study area was 27.5% and 34.5% for the KARSTLOP-AHO and KARSTLOP methods, respectively. The results of KARSTLOP–AHP method are in accordance with the discharge of selected springs in the study area and budget reports.
Fluvial Acoustic Tomography System (FATS) as an advanced technology acquires continuous streamflow data in rivers and estuaries even during floods. However, the acoustic signals are dramatically ...attenuated by suspending sediments which this problem is a new field of study. In this study, we propose a new equation to estimate the maximum applicable measurement distances (MAMDs). It is based on the cross-sectional suspended sediment concentration () and the particle sizes on the 30-kHz FATS. Our study results show that MAMD might be 2,380 m in the clear water. Moreover, the streamflow monitoring can be perfectly done while is less than 12.67 kg/m3 with the particle radii of 3 μm, when the horizontal distance between two acoustic stations is 100 m. Also, the acoustic signals are not decayed if the particle radii equal to 20 mm and the maximum is 6.6 kg/m3. This study highlights the performance of FATS in the presence of high and provides a better perspective of applying FATS in different rivers with high variability of .
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•Simultaneous inversion of flow, solute, and heat was made by CFPv2 karst model.•Conduit-sinkhole dynamic was crucial in successful simulation of Sheshpeer aquifer.•Extensive conduit ...volume storage and likely conduit systems restriction were implied.•A proof of concept for applicability of discrete-continuum modeling was provided.
This research presents the first application of a distributed discrete-continuum numerical model for simultaneous inversion of long-term spring flow in conjunction with solute- and heat-transport signatures, in a large-scale karst system. The MODFLOW-2005 CFPv2 code was adopted for this reason, utilizing PEST for automated inversion. Taking the principal of model parsimony into account, simulations were performed at two stages, testing likely conceptual models based on the hydro-geological understandings. At the first stage, simple yet realistic conceptual models were setup considering different probable variants of conduit geometries. Results of this stage highlights the importance of sinkhole-spring dynamics, in the recorded spring signatures; such that, successful simultaneous calibration of all spring signatures could not be obtained unless high linkage of conduits to the sinkholes all over the catchment was adopted. Subsequently, some additional rational complexity was added in order to achieve a more demonstrable model of the karst system, as the second stage. Model selection criteria, fitting statistics and reasonableness of calibrated parameters were assessed, at this stage. Although one of the model variants could statistically represent all observations with reasonable parameter values and high agreement with catchment hydrogeological perspective, it still cannot be approved as a predictive tool, unless field measurements on conduit system characteristics and matrix hydraulic parameters, as well as long-term observation of aquifer physicochemical signatures be collected for further validation/improvement of conceptual and numerical model. Achieved simultaneous inversion results can serve as a proof of concept for applicability of physically based discrete-continuum modeling approach for flow and transport modeling in karst.
Despite substantial drought conditions in the karst critical zone (KCZ), the KCZ landscapes are often covered with forest woody plants. However, it is not well understood how these plants balance ...water supply and demand to survive in such a water-limited environment. This study investigated the water uptake and transpiration relationships of four coexisting woody species in a subtropical karst forest ecosystem using measurements of microclimate, soil moisture, stable isotopes (δ18O, δ2H, and δ13C), intrinsic water-use efficiency (WUEi), sap flow, and rooting depth. The focus was on identifying differences within- and between-species across soil- and rock-dominated habitats (SDH and RDH) during the rainy growing season (September 2017) and dry season (February 2018). Species across both habitats tended to have higher transpiration with lower WUEi during the rainy season and lower transpiration with higher WUEi during the dry season. Compared to those in the SDH, species in the RDH showed lower transpiration with higher WUEi in both seasons. The dominant water sources were soil water and rainwater for supporting rainy-season transpiration in the SDH and RDH, respectively, and groundwater was the main water source for supporting dry-season transpiration in both habitats. A clear ecohydrological niche differentiation was also revealed among species. Across both habitats, shallower-rooted species with higher soil-water uptake, compared to deeper-rooted species with higher groundwater uptake, showed higher transpiration and lower WUEi during the rainy season and vice versa during the dry season. This study provides integrated insights into how forest woody plants in the KCZ regulate transpiration and WUEi in response to drought stress through interactions with seasonal water sources in the environment.
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•This study was conducted using δ18O, δ2H, δ13C, WUEi, transpiration (Et), and rooting depth.•Water uptake in habitats shifts seasonally due to limited water supply in surface pools.•Et and WUEi variations in habitats are influenced by seasonal shifts in water uptake.•Regulation of Et and WUEi is stricter in RDH than in SDH due to lower soil water supply.•Et, WUEi, and water-uptake vary seasonally among species with different rooting depths.
Groundwater is inevitable for agricultural production in the Indus Basin of Pakistan. Its management on sustainable basis is only possible by careful appraisal of its recharge potential and dynamics. ...This study aimed at exploring pixel-based groundwater recharge at 1 km² spatial resolution using remote sensing data through water balance method. Moreover, spatially distributed groundwater abstractions are estimated by new approach with the aid of remote sensing data and results are compared with the conventional utilization factor method. Groundwater abstraction estimation from conventional utilization factor method overstates results both for kharif and rabi cropping seasons. Recharge results obtained from water balance method and water table fluctuation approach are comparable both at irrigation subdivision and 1 km² spatial scales. During the kharif cropping seasons, rainfall is the main source of recharge followed by field percolation losses while for rabi cropping seasons, canal seepage remains the major source. Net groundwater recharge is mainly positive during all kharif seasons. A gradual increase in groundwater level is observed in major parts of the study area. Improvement in results from water table fluctuation method is possible by better distribution and increased intensity of piezometers while for water balance approach, it is possible by adopting alternative buffer zones for canal seepage. Detailed sensitivity and uncertainty analyses of input/output variables are needed to present the results with confidence interval and hence to support sustainable and economical operation of irrigation system.
•Transfer coefficient is defined by a new equation based on recession coefficient.•The proposed equation is validated by idealized and real karst modeling.•The relation between recession-transfer ...coefficients is affected by flow regime.•Calibration of inverse modeling is improved using recession curve analysis.
Using the reservoir model theory, this study developed an equation for the relationship between the transfer and recession coefficients under a matrix-restrained flow regime. Assuming Darcy's law, the proposed equation was developed based on conventional parameters of karst systems, such as recession coefficient, specific yield, and catchment area. Firstly, the equation was evaluated through forward and inverse modeling of an idealized karst system with MODFLOW-2005 Conduit Flow Process (CFP) and KarstMod, respectively. Then, calibration of a KarstMod and a CFP model of the Baget karstic watershed in France was carried out to check the efficiency of the developed equation.
Results of the first step showed that the optimal value of the transfer coefficient based on KarstMod for the linear transfer flow is very close to the baseflow recession coefficient values. Therefore, the transfer coefficient in KarstMod may be considered as the recession coefficient from the matrix to the conduit compartment. Moreover, substituting these two coefficients in the developed equation caused less than 10% errors in estimating the transfer coefficients assigned to the idealized models in CFP. In addition, adding the recession coefficient as prior information in the calibration process affects the recession coefficient of the simulated time series and provides a reliable evaluation of the internal dynamics of the system. Therefore, the results of this research show that the recession coefficients can be used as an initial estimate of the transfer coefficient in the baseflow condition. This achievement can significantly assist the discrete-continuum model calibration and further support the water balance calculations based on the recession data.
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