城市绿地水土流失问题及应对策略

Soil and Water Loss Issues and Mediating Strategies in Urban Green Land

摘要: 城市绿地是人居环境的重要组成部分，是城市景观系统发挥水土保持功能的关键景观单元。分析了城市绿地水土流失的原因，针对性地提出城市绿地水土流失的调控策略。因微地形、植被结构、利用强度和管理措施等多方面的原因容易导致水土流失，也是采取优化措施的切入点。本研究提出了如下策略：在地形优化方面应降低坡度、避免连续长坡；植被结构优化方面应合理配置水平方向林、灌、草景观单元，在垂直方向应尽量做到林–灌–草分层植被的组合；绿地利用强度管控方面，应根据植被的承受能力来采取与生长阶段相适应的利用强度管控措施，尽可能在冬春降低游人踩踏频率，在夏秋可以适当放宽踩踏频率；在绿地管护方面，应避免大水漫灌，采用喷灌或者滴灌方式，同时保留部分凋落物。

Abstract: Green land is a critical component of the urban system and a key landscape unit for the urban landscape system to perform soil and water conservation functions. This paper analyzed the causes of soil erosion in urban green spaces, and proposed mediating strategies for controlling soil erosion in green land. As a consequence of weakness in microtopography, vegetation configuration, utilization intensity, and daily management, green land often suffers soil and water loss. Correspondingly, the countermeasures are given. First, the microtopography can be optimized by alleviating the slope gradient and segmenting the elongated hillslopes. Second, in optimizing vegetation structure, the horizontal layout of trees, shrubs, and grass landscape units should be reasonably configured, and vertically, a layered combination of trees, shrubs, and grass should be adopted as much as possible. Third, for management of the utilization intensity of green land, coincidence with the seasonality of vegetation is necessary. Cutting down the trembling frequency in spring and winter, and freeing the trembling frequency in summer and autumn are critical. Besides, as to the management of green land, flooding irrigation should be avoided, and instead, sprinkler or drip irrigation should be employed while retaining some litterfall.