Prediction of sediment,particulate nutrient and dissolved nutrient concentrations in a dry tropical river to provide input to a mechanistic coastal water quality model

A Generalised Additive Modelling (GAM) approach is applied to prediction of both particulate and dissolved nutrient concentrations in a wet-tropical river (the Fitzroy River, Queensland, Australia). In addition to covariant terms considered in previous work (i.e. flow, discounted flow and a rising-falling limb term), we considered several new potential covariates: meteorological and hydrological variables that are routinely monitored, available in near-real time, and were considered to have potential predictive power. Of the additional terms considered, only flows from three tributaries of the Fitzroy River (namely, the Nogoa, Comet and Isaac Rivers) were found to significantly improve the model. Inclusion of one or more of these additional flow terms greatly improved results for dissolved nitrogen and dissolved phosphorus concentrations, which were not otherwise amenable to prediction. In particular, the Nogoa sub-catchment, dominated by pasture for cattle, was found to be important in determining dissolved inorganic nitrogen and phosphorus concentrations reaching the river mouth. This insight may direct further research, including future refinement of processed-based catchment models. The GAMs described here are used to provide near real-time river boundary conditions for a complex coupled hydrodynamic and biogeochemical model of the Great Barrier Reef Lagoon, and can be coupled with a forecasting hydrological model to allow integrated forecasting simulations of the catchment to coast system.     

Possibilities and problems with the use of models as a communication tool in water resource management

Politicians and policy-makers, as well as modellers, often nurses an expectation that model derived results is an objective source of information that can be used to support decisions. However, several prerequisites have to be dealt with in order to ensure that models can be used as legitimate and efficient tools in water resource management. Based on empirical material from recent studies on the use of models in stakeholder dialogues, mainly focusing on catchment nutrient transport, two central problems are identified: (a) Models are laden with choices and thus depend on assumptions and priorities of modellers. (b) There are several factors that influence ability and willingness of stakeholders (as information recovers) to criticize or accept results of the modelling exercise. Recognized factors likely to influence stakeholders' acceptance of model derived results include issues at stake, stakeholders' ability to criticize model derived information, and their trust in the institutions that have developed or applied the used models. Identified prerequisites for successful use of models in integrated water resource management include: consideration of user relevance, awareness of and preparedness to handle constraints linked to communication of model-based results, transparency of used models and data and of involved uncertainties, mutual respect between experts and stakeholders and between involved stakeholder groups, a robust institutional network, and sufficient time for dialogues. Development and use of strategies for participatory modelling, based on a continuous dialogue between experts and stakeholders is recommended as a way to facilitate that the prerequisites for a successful use of models in water resource management are fulfilled.     

DEM分辨率对山洪淹没模拟影响

DEM是表征地形状况的重要指标,在山洪淹没模拟中起着重要作用。以2016年7月19日发生在河北省石家庄市井陉县西部山区的特大暴雨山洪事件为研究对象,利用HEC-HMS水文模型和FLO-2D水动力模型,设置5种DEM分辨率方案(30、20、15、10、5 m),从淹没范围和淹没水深两方面分析了DEM分辨率对山洪淹没模拟的影响,并从模型运行时间角度对其运行效率进行了评估。研究表明:DEM分辨率越高,则淹没范围越小,平均淹没水深越大,即模型模拟精度越高,山洪事件的淹没范围及水深越接近于实际调查情况(DEM分辨率为30和5 m时,淹没范围及淹没深度的模拟精度分别为0.56和0.41、0.76和0.79);随着DEM分辨率的提高,尤其从10 m提高至5 m时,模拟结果差异减少,模拟精度的增幅也减小,淹没范围和水深的精度增幅分别为2.70%和3.94%;DEM分辨率越高,则模型运行时间越长,模型运行效率越低,5 m DEM方案下的运行时间为30 m DEM方案的700倍。综合考虑模拟精度及模拟时间,10 m分辨率的DEM对山洪淹没模拟、风险评估及预警预报等更为适用。     

Two new characteristic parameters for runoff computation

A method capable of estimating the hydrograph from a prescribed storm for a practical mild slope upstream catchment is proposed. This method makes use of two new characteristic parameters, andS, in conjunction with the kinematic wave equation to compute lateral inflows of the main stream of the catchment. The depth profile of overland flow at any instant within the catchment and hydrograph at any location can be easily found. Lag times for individual lateral inflows are then considered and are linearly combined to obtain the hydrograph at the outlet of the catchment or depth profile of the main stream at any instant. The validity of the excess rainfall-surface runoff linear relationship in this study has also been verified with Tatsunokuchiyama catchment, and it shows good results for this computed runoff.     

Assessment of future climate change impacts on hydrological behavior of Richmond River Catchment

This study evaluated the impacts of future climate change on the hydrological response of the Richmond River Catchment in New South Wales (NSW), Australia, using the conceptual rainfall-runoff modeling approach (the Hydrologiska Byrans Vattenbalansavdelning (HBV) model). Daily observations of rainfall, temperature, and streamflow and long-term monthly mean potential evapotranspiration from the meteorological and hydrological stations within the catchment for the period of 1972–2014 were used to run, calibrate, and validate the HBV model prior to the streamflow prediction. Future climate signals of rainfall and temperature were extracted from a multi-model ensemble of seven global climate models (GCMs) of the Coupled Model Intercomparison Project Phase 3 (CMIP3) with three regional climate scenarios, A2, A1B, and B1. The calibrated HBV model was then forced with the ensemble mean of the downscaled daily rainfall and temperature to simulate daily future runoff at the catchment outlet for the early part (2016–2043), middle part (2044–2071), and late part (2072–2099) of the 21st century. All scenarios during the future periods present decreasing tendencies in the annual mean streamflow ranging between 1% and 24.3% as compared with the observed period. For the maximum and minimum flows, all scenarios during the early, middle, and late parts of the century revealed significant declining tendencies in the annual mean maximum and minimum streamflows, ranging between 30% and 44.4% relative to the observed period. These findings can assist the water managers and the community of the Richmond River Catchment in managing the usage of future water resources in a more sustainable way.     

Application of the Soil and Water Assessment Tool for six watersheds of Lake Erie: Model parameterization and calibration

The Soil and Water Assessment Tool (SWAT), a physically-based watershed-scale model, holds promise as a means to predict tributary sediment and nutrient loads to the Laurentian Great Lakes. In the present study, model performance is compared across six watersheds draining into Lake Erie to determine the applicability of SWAT to watersheds of differing characteristics. After initial model parameterization, the Huron, Raisin, Maumee, Sandusky, Cuyahoga, and Grand SWAT models were calibrated (1998-2001) and confirmed, or validated (2002-2005), individually for stream water discharge, sediment loads, and nutrient loads (total P, soluble reactive P, total N, and nitrate) based on available datasets. SWAT effectively predicted hydrology and sediments across a range of watershed characteristics. SWAT estimation of nutrient loads was weaker although still satisfactory at least two-thirds of the time across all nutrient parameters and watersheds. SWAT model performance was most satisfactory in agricultural and forested watersheds, and was less so in urbanized settings. Model performance was influenced by the availability of observational data with high sampling frequency and long duration for calibration and confirmation evaluation. In some instances, it appeared that parameter adjustments that improved calibration of hydrology negatively affected subsequent sediment and nutrient calibration, suggesting trade-offs in calibrating for hydrologic vs. water quality model performance. Despite these considerations, SWAT accurately predicted average stream discharge, sediment loads, and nutrient loads for the Raisin, Maumee, Sandusky, and Grand watersheds such that future use of these SWAT models for various scenario testing is reasonable and warranted.     

受下游水位顶托下的太湖流域西苕溪中下游水位预报研究

西苕溪位于太湖流域中上游地区,由于其中下游河床比降较小,且受太湖水位顶托以及东苕溪导流干扰,经常发生洪涝淹没灾害,造成了严重的社会经济损失,长期以来该河流洪水预报工作显得尤为重要,但由于河流中下游水位流量关系复杂,该区域以水位预报为核心的洪水预报始终是其难点之一.文中探讨了研究区受下游洪水顶托影响下的洪水预报方法,采用20世纪80年代以来的12场较大洪水资料,建立了西苕溪流域下游水位混合回归预报模型,并利用后期的8场洪水加以验证分析.实例验证表明,对于西苕溪这类水文规律复杂的流域,系统的混合回归模型具有简单方便、模拟精度高等特点.     

三峡地区的水土流失与水土保持

三峡地区沟壑纵横、地形破碎，交通不便、生态环境恶化，经济和社会发展一直比较缓慢，三峡工程的兴建，给三峡地区的经济和社会发展带来了良好的机遇，了对这一地区的农业生产和生态保护提出出更高的要求。１９８８年，国务院批准将长江上游列为国家水土保持重点防治区，这是增强三峡地区的农业基础设施改善生态环境，实现该地区经济可持续发展的基础工程。     

The Management of Water Colour in Peatland Catchments

The problems of water-colour management in peatland catchments are discussed. Colour may be managed in three areas of the reservoir catchment system: on the catchment itself, in the channel/conduit system and within the reservoir. Whilst a number of workers have considered the management of catchment areas and some have evolved tributary turnout strategies, no previous research has considered the role of the reservoir in the amelioration or enhancement of water colour. The management of water colour at Thornton Moor catchment (near Bradford) is described. In this catchment a staged approach has been adopted, with colour being managed in an integrated manner at three stages along the catchment/conduit/reservoir system.