屋顶花园雨水利用系统设计与实践

Design and practice of rainwater utilization system for roof garden

该文意在探讨利用屋面雨水对屋顶花园进行灌溉的可行性。以北大荒集团某酒店屋顶花园为例,从植物需水量、雨水可收集量、蓄水池容量及雨水收集系统等方面进行屋面雨水回收利用设计,利用彭曼-蒙特斯公式计算屋顶花园植物需水量,结果表明:5-10月屋顶花园植物需水总量为3521.78m3,各月份间差异较大,10月份量最小仅为361.8m3,6月份量最大为729.6m3;同期可收集屋面雨水总量为2179.3m3,并据雨水径流总量与初期弃流量产生的径流量设计蓄水池容量为131m3;将收集雨水全部用于屋顶花园绿地灌溉,能节省61.88%灌溉用水;据此,采用工程技术为屋顶花园设计雨水收集系统及自动灌溉系统,对屋顶花园雨水收集量与灌溉量的水量平衡分析结果表明:利用该自动灌溉系统可节约灌溉用水67.20%,雨水利用率可达54.55%,该设计对北方干旱地区屋顶花园雨水回用技术设计具一定的实用价值和应用前景。

In recent years, urban landscape has changed from ground greening to the roof three-dimensional greening with the rapid development of landscaping in China, and a lot of roof gardens have been built to open up the new development space for the landscape in cities. Shortage of water exists in many cities, and the city water stress will turn out because of the increasing roof gardens. To solve these problem, taking the roof garden of Beidahuang group hotel as an example, we would intend to discuss the feasibility of using roof rainwater for irrigating roof garden, and design the collection and utilization of the roof rainwater following the plant evapotranspiration （ET）, the rainwater collection quantity, the reservoir capacity and rainwater collection systems. Firstly, the plant water requirement in roof garden was calculated using Penman-Monteith formula and garden coefficient methods. The results showed that the total of ET was 3 521.78 m3 from May to October, and which was significantly different from only 361.8 m3 in October to 729.6 m3 in June. Secondly, the collection rainwater in roof garden and the next building roofs was calculated, it showed that the total collected roof rainwater was 2 179.3 m3. The reservoir capacity was designed at 131 m3 according to the stormwater runoff volume and the first-flush runoff quantity. It could save 61.88% of irrigation water if the collected rainwater was used to irrigate for roof garden. Therefore, the rainwater collection systems and the automatic irrigation systems for the roof garden were designed using engineering technology. The rainwater collection systems included rainwater collecting ports, transporting pipelines, split-flow pool, purifying systems and reservoirs to collect rainwater in the roofs of the buildings, split-flow runoff, purify runoff rainwater, and store rainwater in the reservoir to use. Automatic irrigation system, included sensor system, central control system, power system, transporting system and communication equipments, the central control system could control the turn-on time and the irrigation quantity to the irrigation system by analyzing the soil moisture signals collected by the sensor system. So the automatic irrigation system could achieve accurate and water-saving irrigation. Finally, taking advantage of this automatic irrigation system could save 67.20% of irrigation water and the rainwater utilization rate was up to 54.55% with the water balance and running results analysis. The new recommendable method of roof garden rainwater collection and utilization proposed in this paper have the important practical value and the application prospects to design the technology for collecting and utilizing rainwater in the north arid area.