Modeling and monitoring of long-term acidification in an upland catchment of the Western Ore Mountains,SE Germany

Modeling and monitoring of acidification patterns in a limed forest catchment in the Ore Mountains, SE Germany are presented. A lumped-parameter model, MAGIC, satisfactorily reproduced the main parameters of stream water chemistry. Despite repeated whole-catchment liming, between 1993 and 1999 stream water pH increased from 4.3 to only 4.6, while calcium concentrations declined slightly. Stream water sulfate concentration declined from 687 to 396 microeq l(-1), and the pronounced effect of deposition decline during the 1990s was probably more important than liming.     

A Regionally Applicable Model for Estimating Flow Velocity at Ungauged River Sites in the UK

Measurements of flow velocity are often required for a broad range of issues surrounding water-resource management, and a velocity-estimation method is therefore desirable where extensive field data are unavailable. This paper presents the development of a model for estimating flow velocity using readily available catchment characteristics, and flow and channel geometry data. The velocity equations were calibrated using UK data, so that their application at any river site in the UK is attainable. The calibrated equation uses the mean flow and the dimensionless magnitude of the flow on the day in question to estimate the mean reach velocity for flows at any river site in the UK.     

Regionalisation of impervious area parameters of urban drainage models

Stormwater drainage models are increasingly being used in design and analysis of urban drainage systems. If these models are to be used for ungauged drainage systems for which no storm and corresponding flow data are available, then the model parameters have to be estimated through regional equations. These regional equations define the model parameters via measurable catchment properties. In this study, regional equations of two impervious area parameters, namely directly connected impervious area percentage (DCIA) and its depression storage (DS_i ), were developed for use in urban drainage models, using 15 gauged urban catchments in Melbourne Metropolitan area (Australia). The ‘small’ storm events of these gauged catchments were first used to calibrate the impervious area parameters, since the ‘small’ storm events produce runoff only from the impervious areas. These calibrated impervious area model parameters were then analysed with several measurable catchment properties to derive the regional equations. The results of the study revealed that DCIA was depended only on household density of the catchment, while DS_i was not correlated with any of the catchment properties analysed.     

Surface runoff estimation over heterogeneous foothills of Aravalli mountain using medium resolution remote sensing rainfall data with soil conservation system‐curve number method: A case of semi‐arid ungauged Manesar Nala watershed

Manesar Nala watershed, having an aerial extent of 71.53 km², was subjected to modelling of its hydrological behaviour for assessing its water resource potential. Modern tools and techniques of Remote Sensing (RS) and Geographic Information System (GIS) were used for assessment of runoff generating potential using the Hydrologic Soil Cover Complex (HSCC) Method [U.S. Department of Agriculture (USDA)‐Soil Conservation System‐Curve Number (SCS‐CN) approach]. RS and GIS were used in generation and integration of thematic maps [such as Land use/Land cover (using LISS‐III data) and Hydrologic Soil Group (HSG), (using soil map of study area) to derive the Curve Number (CN) for simulating Runoff (R_o)]. The daily rainfall (P) data for the study period 2002–2015 were acquired from NOAA Climate Prediction Center (NCPC). Corresponding R_o from the watershed for intense storm events for 14 years were calculated through RS and GIS. GIS and SCS‐CN model was employed for modelling the runoff production to study its hydrological behaviour. The study showed that the Manesar Nala watershed was having a composite Curve Number – II (CN_II) value of 82.5 for normal conditions. For dry and wet conditions these values were estimated at 66.44 (CN_I) and 91.56 (CN_III), respectively. This investigation showed that Manesar Nala watershed exhibited an annual average (of 14 years, 2002–2015) R_o volume of 4 542 514.37 m³ based on the average annual rainfall (P) of 0.72 m (720 mm). The average annual surface runoff (R_o) was predicted to be approximately 0.21 m with annual runoff coefficient (C_R) of 0.29. During the study, we also found a strong correlation ‘r’ between satellite driven P and R_o from NRCS‐CN method of the order of 0.94. The methodology so developed has the potential to be used in other similar ungauged watersheds in the same agro‐climatic conditions for the purpose of planning of watershed conservation measures and other developmental activities.     

Regionalisation of physically-based water balance models in Belgium. Application to ungauged catchments

More than 60 catchments from Northern Belgium ranging in size from 16 to 3160 km² have been studied by means of a physically-based stochastic water balance model. The parameter values derived from calibration of the model were regionally mapped for the study region. Associations between model parameters and basin lithological characteristics were established and tested. The results show that the simple conceptual monthly water balance model with three parameters for actual evapotranspiration, slow and fast runoff is capable either to generate monthly streamflow at ungauged sites or to extend river flow at gauged sites. This allows a fairly accurate estimation of monthly discharges at any location within the region.     

DDRM模型在渠江流域的应用研究

为了进一步探究分布式水文模型(DDRM)的适用性,基于渠江流域的数字高程模型(DEM),提取了研究区域的边界、河网水系,计算了研究区域的地形指数;然后采用基于DEM的DDRM模型进行流域降雨-径流过程模拟,并用确定性系数、洪峰相对误差、峰现时间误差等对DDRM模型的模拟精度进行了评价;同时,对比分析了不同DEM栅格分辨率(1 km和2 km)对模型模拟精度的影响。结果表明:基于上述2种分辨率的DDRM模型在渠江流域降雨-径流模拟中均取得了较好的模拟效果,其中基于1 km栅格的DDRM模拟精度略优于2 km栅格。DDRM模型结构简单,参数较少、物理过程明确,而且能够模拟流域土壤含水量和径流量的空间分布,可为缺资料地区水文模拟提供一种新的方法。     

中小流域时空变源混合产流模型及参数区域化方法研究

针对山丘区中小流域洪水预报面临的产流机制混合多变和模型参数难以获取的问题,提出了适用于缺资料地区的中小流域时空变源混合产流模型和基于机器学习CART的参数区域化方法。在小流域地貌水文响应单元划分基础上,利用GARTO非饱和下渗计算模型,从超渗/蓄满机制的平面混合、垂向混合和时段混合三个方面构建时空变源混合产流模型,并采用机器学习CART方法进行模型参数区域化研究。选取不同地貌类型区的15个流域和河南省19个小流域实测降雨径流资料分别对模型适用性和参数区域化方法进行了验证。结果表明,通过与国内外8个水文模型的对比验证,时空变源混合产流模型模拟平均纳什系数为0.78,比其他模型提高约20%;利用本模型和CART参数区域化方法在河南省19个流域计算的平均纳什系数为0.70,比参数随机移植结果提高了35%,本模型和参数区域化方法在山丘区中小流域洪水模拟中应用效果较好。     

无资料小流域地区可能最大洪水计算研究

本文采用当地推理公式法,借鉴相近地区相似水文特征的洪峰流量经验公式估算无资料小流域河道最大可能洪水,用恒定流水面线法计算某核电厂厂址处由最大可能洪水产生的洪水位。用水力学方法计算可能最大洪水为既考虑河道内区间回水情况,同时也反映了河道的水力学特性,计算结果更接近实际情况。     

亚热带农业小流域暴雨过程硝态氮迁移特征及水文示踪研究

为揭示亚热带丘陵区农业小流域暴雨过程中硝态氮迁移规律及其主要水文输送途径,本研究通过对紫色土丘陵区典型农业小流域典型暴雨过程跨尺度(从3~1 236 hm2)连续监测,分析径流硝态氮迁移动态特征及其尺度效应,并对比δ18O和硝态氮作为示踪剂的端元混合分析(EMMA)解析结果,探讨硝态氮作为暴雨过程水文示踪剂的可行性。结果表明:(1)两场暴雨事件中源头小流域苏荣小流域(含集镇污水)径流中硝态氮浓度最高,而到达梯级小流域出口处(万安小流域)硝态氮浓度最低,林地来水的贡献是较大尺度小流域径流硝态氮浓度降低的主要原因,坡耕地壤中流补给可能是径流消退过程中硝态氮出现浓度峰值的主要原因。(2)EMMA模型解析结果显示:δ18O与硝态氮均能示踪农业小流域径流消退期间壤中流补给过程;但硝态氮在受人居活动强烈影响子流域的示踪应用需谨慎。以农业为主的亚热带丘陵区小流域中,硝态氮具有同时作为环境效应指示剂和水文示踪剂的潜力,但其应用效果仍有待于进一步验证。     

Effects of hydrological changes on cooperation in transnational catchments: the case of the Syr Darya

Water allocation along the Syr Darya River may be affected by climate change. Here we statistically model cooperation strategies, country profits, and sensitivity of cooperation, showing that the hydrological regime affects transboundary cooperation. Climate change in the twenty-first century may reduce glacial cover, and reducing stream flows, decreasing chances of cooperation and potentially raising conflicts. Comparison with other transboundary catchments in Central Asia indicates moderate-to-high risk of conflicts for the Syr Darya. A template is provided for assessment of the stability of cooperation in the Syr Darya basin, and in catchments similarly dependent on water availability.