Simulation of Rainfall-Underground Outflow Responses of a Karstic Watershed in Southwest China with an Artificial Neural Network

Chen, Guihai; Xi,; Dan, Cai; Hao, Dan; Qingqing,; Zhang, Bo; Zhicai,; Shi, Jianrong; Peng, Peng

doi:10.1061/41003(327)41

Cited by 7 publications

(10 citation statements)

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“…As shown in Figure , the application of fertilizer or/and manure as well as biogenic CO 2 , which is a by‐product of microbial respiration, can influence carbon isotopic signals to some extent. In the karstic region of Southwestern China, the thin soils and vadose zone with weak buffering enable contaminants, such as NO 3 − , to migrate quickly within the surface–underground system (Chen et al ., ; Perrin et al ., ). This may be responsible for the observation that NO 3 − concentrations in UGW were higher than those in SFS, which is inconsistent with results in non‐karstic areas (Li et al ., ).…”

Section: Discussionmentioning

confidence: 97%

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Spatiotemporal variations of dissolved inorganic carbon and controlling factors in a small karstic catchment, Southwestern China

Qin

Yue

et al. 2019

Earth Surf Processes Landf

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Dissolved inorganic carbon (DIC) is the most important carbon component in karst aquatic system where fluid is highly transmissive, but has rarely been examined in the subtropical karst critical zone (K‐CZ). In this study, concentrations of dissolved solutes and isotopic compositions of DIC (δ13CDIC) at 11 sites of a 73.4 km2 karstic catchment in Southwestern China were analysed monthly in order to uncover the spatiotemporal variations of both DIC and its dominant sources, and to identify relevant controlling factors. Both DIC concentrations and δ13CDIC were highly variable, ranging from 2.52 to 5.85 mmol l−1 and from −15.7 to −4.5‰, respectively. DIC in underground water (UGW) was higher in concentration and more depleted in 13C compared to surface water (SFS). DIC concentrations showed an inconsistent seasonal trend with other solutes, with higher values in the wet season at some sites. δ13CDIC values were lower in the wet season than in the dry season. The results of mixing model IsoSource revealed spatiotemporal patterns of DIC sources. During the dry season, carbonate weathering was the primary contributor to DIC in UGW (excluding in the middle reaches). However, during the wet season, soil CO2 was the dominant source of DIC in both UGW and SFS, and it was higher than in the dry season. Overall, there are significant spatiotemporal disparities and highly transmissive characteristics of both DIC and its sources in the K‐CZ, which are controlled by multiple factors. This study also highlights that rainfall may play a crucial role in accelerating carbon dynamics in the K‐CZ. High‐frequency sampling campaigns in high‐flow periods and deep analyses are needed in future work to elucidate the related processes and mechanisms. © 2019 John Wiley & Sons, Ltd.

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Section: Discussionmentioning

confidence: 97%

“…The lithology of this catchment is primarily middle Triassic carbonates, with abundant but minor clastic sedimentary rocks and minor strata of interbedded gypsum (Chen et al ., ; Li et al ., ). The Houzhai catchment covers 73.4 km 2 , of which 51.0% is arable land, followed by forest (32.8%) and built land (12.1%).…”

Section: Methodsmentioning

confidence: 97%

Spatiotemporal variations of dissolved inorganic carbon and controlling factors in a small karstic catchment, Southwestern China

Qin

Yue

et al. 2019

Earth Surf Processes Landf

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“…The focused recharge to underground channels through sinkholes has been widely identified by karst researchers. In the Houzhai catchment, the hydrological function of sinkholes was estimated by modelling the surface flow assumed to be captured by sinkholes FIGURE 9 Composition variation of discharge on the left and mass of Ca + Mg on the right for Muzhudong (MZD), Laoheitan (LHT), and Maoshuikeng (MSK) (Meng, Wang, Su, & Yu, 2008) or calculation of the fast recharge to underground channels reflecting the sinkhole influence (Chen, Chen, Hao, Zhang, & Shi, 2008). However, these studies did not include the dual flow systems and were based on the assumption that the influence of sinkholes is constant; here, we show that the contribution of direct infiltration to the underground channel (I f,t Table 2, is about 2,712 t/yr) and other studies in the catchment.…”

Section: Discussionmentioning

confidence: 99%

Catchment‐scale conceptual modelling of water and solute transport in the dual flow system of the karst critical zone

Zhang

Chen

Soulsby

2017

Hydrological Processes

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Hydrological and hydrochemical processes in the critical zone of karst environments are controlled by the fracture‐conduit network. Modelling hydrological and hydrochemical dynamics in such heterogeneous hydrogeological settings remains a research challenge. In this study, water and solute transport in the dual flow system of the karst critical zone were investigated in a 73.5‐km2 catchment in southwest China. We developed a dual reservoir conceptual run‐off model combined with an autoregressive and moving average model with algorithms to assess dissolution rates in the “fast flow” and “slow flow” systems. This model was applied to 3 catchments with typical karst critical zone architectures, to show how flow exchange between fracture and conduit networks changes in relation to catchment storage dynamics. The flux of bidirectional water and solute exchange between the fissure and conduit system increases from the headwaters to the outfall due to the large area of the developed conduits and low hydraulic gradient in the lower catchment. Rainfall amounts have a significant influence on partitioning the relative proportions of flow and solutes derived from different sources reaching the underground outlet. The effect of rainfall on catchment function is modulated by the structure of the karst critical zone (e.g., epikarst and sinkholes). Thin epikarst and well‐developed sinkholes in the headwaters divert more surface water (younger water) into the underground channel network, leading to a higher fraction of rainfall recharge into the fast flow system and total outflow. Also, the contribution of carbonate weathering to mass export is also higher in the headwaters due to the infiltration of younger water with low solute concentrations through sinkholes.

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“…Groundwater in deep aquifers flows through interconnected conduits and cave systems, and eventually flows out of the basin as a spring (Figure 1). Due to rich rock fractures and the underground conduit system, streamflow hydrographs for the karst region of southwest China present a steep rise and decline (Chen et al , 2008).…”

Section: Methodsmentioning

confidence: 99%

Modelling hydrological processes influenced by soil, rock and vegetation in a small karst basin of southwest China

Zhang

Chen

Ghadouani

et al. 2011

Hydrological Processes

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Abstract:Hydrological processes in karst basins are controlled by permeable multimedia, consisting of soil pores, epikarst fractures, and underground conduits. Distributed modelling of hydrological dynamics in such heterogeneous hydrogeological conditions is a challenging task. Basing on the multilayer structure of the distributed hydrology-soil-vegetation model (DHSVM), a distributed hydrological model for a karst basin was developed by integrating mathematical routings of porous Darcy flow, fissure flow and underground channel flow. Specifically, infiltration and saturated flow movement within epikarst fractures are expressed by the 'cubic law' equation which is associated with fractural width, direction, and spacing. A small karst basin located in Guizhou province of southwest China was selected for this hydrological simulation. The model parameters were determined on the basis of field measurement and calibrated against the observed soil moisture contents, vegetation interception, surface runoff, and underground flow discharges from the basin outlet. The results show that due to high permeability of the epikarst zone, a significant amount of surface runoff is only generated after heavy rainfall events during the wet season. Rock exposure and the epikarst zone significantly increase flood discharge and decrease evapotranspiration (ET) loss; the peak flood discharge is directly proportional to the size of the aperture. Distribution of soil moisture content (SMC) primarily depends on topographic variations just after a heavy rainfall, while SMC and actual ET are dominated by land cover after a period of consecutive nonrainfall days. The new model was able to capture the sharp increase and decrease of the underground streamflow hydrograph, and as such can be used to investigate hydrological effects in such rock features and land covers.

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Simulation of Rainfall-Underground Outflow Responses of a Karstic Watershed in Southwest China with an Artificial Neural Network

Cited by 7 publications

References 0 publications

Spatiotemporal variations of dissolved inorganic carbon and controlling factors in a small karstic catchment, Southwestern China

Spatiotemporal variations of dissolved inorganic carbon and controlling factors in a small karstic catchment, Southwestern China

Catchment‐scale conceptual modelling of water and solute transport in the dual flow system of the karst critical zone

Modelling hydrological processes influenced by soil, rock and vegetation in a small karst basin of southwest China

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