Unmanned aerial vehicles for planning rooftop rainwater harvesting systems: a case study from Gurgaon, India

Abstract

Rooftop rainwater harvesting systems (RRWHS) effectively provide water access by storing precipitated water. The amount of water harvestable using these systems is proportional to the availability of rooftop areas in the region. The use of satellite imagery has gained traction in recent times considering the challenges in conducting a manual survey to determine the rooftop area. However, the limitations on spatial resolution impaired stakeholders from conducting similar assessments in areas with small residential units. In this regard, the use of unmanned aerial vehicles (UAVs) providing high-resolution spatial imagery for the delineation of rooftops of all scales has become popular. The present study is an attempt to utilize UAV-generated orthomosaics to estimate the harvestable quantity of rainwater for setting up an RRWHS. A study area in the Gurgaon district, India, is selected, and the steps involved in estimating the quantity of water harvestable using UAVs are demonstrated. In addition to these computations, a suitable site for constructing the storage unit is identified with the aid of a weighted overlay technique implemented using a Geographic Information System. The results from the study show that nearly 11,229 m3 of water can be harvested per year in the study site using the RRWHS. HIGHLIGHTS An efficient contactless image acquisition framework for rooftop rainwater harvesting systems was proposed.; Effective utilization of UAV-generated images for rooftop area evaluation was demonstrated using the Structure-from-Motion technique.; A multi-criteria decision-making strategy for site selection of the rainwater harvesting system was developed.; Challenges associated with unsupervised classification for rooftop area delineation in rainwater harvesting were demonstrated.;

Keywords

• orthomosaic
• rooftop rainwater harvesting system (rrwhs)
• unmanned aerial vehicle (uav)