SUSTAINABLE HOUSE-SCALE PASSIVE RAINWATER CAPTURE LANDSCAPE IN THE DESERT SOUTHWEST

A passive rainwater harvesting technique was used to design a sustainable landscape for a residential lot located in the desert. The design was adapted to the Desert Southwest region of the United States based on thirty years of daily historical climate data including precipitation and reference evapotranspiration (ET0). Four cities including El Paso, TX, Albuquerque, NM, Phoenix, AZ, and Pahrump, NV, were selected to represent the area. The residential lot was broken up into micro-watersheds reflecting the runoff of water from each separate portion of the house roof, driveway, and lawn area. The paper explains in detail the design steps for one of the micro-watersheds where water retention and infiltration structures were distributed throughout the soil area to capture stormwater runoff close to its source. A passive rainwater capture landscape was obtained by using the stormwater captured in the infiltration structures and stored in the surrounding soil. Native vegetation (shrubs and trees) will use this water exclusively for growth. These plants will not require watering once their root establishment period has passed, except in extreme droughts. Meanwhile, stormwater discharge from the lot will decrease and the groundwater recharge will increase. Results indicate that the current urban water budget can be made sustainable by replacing watering of landscape by municipal water with harvested stormwater. This results in a relatively lush and shady environment even in desert climates. The success is an artifact of the tendency of urban watersheds to increase the volume of stormwater relative to pre-development conditions.