Schütte S, Schulze R E
Centre for Water Resources Research, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa.
Centre for Water Resources Research, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa.
J Environ Manage. 2017 Jul 1;196:527-543. doi: 10.1016/j.jenvman.2017.03.028. Epub 2017 Mar 25.
Significant land use changes from natural/agricultural to urban land uses have been proposed within the Mpushini/Mkhondeni sub-catchments of the uMngeni Catchment in South Africa. A better understanding of the influences which such land use changes are likely to have on hydrological flows, is required, in order to make informed land use decisions for a sustainable future. As a point of departure, an overview of linkages between urbanisation and hydrological flow responses within this sub-humid study area is given. The urban characteristics of increased impervious areas and the potential return flows from transfers of potable water from outside the catchment were identified as being important in regard to hydrological flow responses. A methodology was developed to model urban response scenarios with urban characteristics as variables, using the daily time-step process based ACRU model. This is a hydrological multi-process model and not an urban hydraulic model and it addresses the landscape as well as the channel components of a catchment, and in addition to runoff components includes evaporation and transpiration losses as outputs. For the study area strong links between proposed urbanisation and hydrological resource flow responses were found, with increases in stormflows, together with increased and more regulated baseflows, and with impacts varying markedly between dry or wet years and by season. The impacts will depend on the fractions of impervious areas, whether or not these are connected to permeable areas, the amount of imported water and water system leaks. Furthermore, the urban hydrological impacts were found to be relatively greater in more arid than humid areas because of changes in the rainfall to runoff conversion. Flow changes due to urbanisation are considered to have important environmental impacts, requiring mitigation. The methodology used in this paper could be used for other urbanising areas.
在南非姆格尼集水区的姆普希尼/姆孔德尼子集水区内，已有人提议进行从自然/农业用地到城市用地的重大土地利用变化。为了做出有利于可持续未来的明智土地利用决策，需要更好地了解此类土地利用变化可能对水文流量产生的影响。作为出发点，本文概述了该半湿润研究区域内城市化与水文流量响应之间的联系。不透水区域增加的城市特征以及集水区外饮用水转移产生的潜在回流，被认为对水文流量响应具有重要意义。本文开发了一种方法，以城市特征为变量，使用基于日时间步长过程的ACRU模型来模拟城市响应情景。这是一个水文多过程模型，而非城市水力模型，它考虑了集水区的景观和河道组成部分，除径流组成部分外，还将蒸发和蒸腾损失作为输出。对于该研究区域，研究发现拟议的城市化与水文资源流量响应之间存在紧密联系，暴雨径流增加，基流增加且调节性更强，其影响在干旱或湿润年份以及不同季节之间存在显著差异。这些影响将取决于不透水区域的比例、这些区域是否与透水区域相连、进口水量以及供水系统的泄漏情况。此外，由于降雨径流转换的变化，在干旱地区，城市化对水文的影响相对大于湿润地区。城市化导致的流量变化被认为具有重要的环境影响，需要加以缓解。本文所采用的方法可用于其他正在城市化的地区。
