Understanding the Concept and the Potential of Roads for Water | 9
Ideally, all such measures and opportunities should be part of the environmental and social management plans of road investments, not only to address risks but also to make use of opportunities. Green Roads programs can go much farther than addressing localized risks and opportunities, however. Green Roads programs are being implemented as large-scale, cross-sectoral climate adaptation and resilience programs affecting agriculture, water and sanitation, water resource management, and landscape management. These Green Roads programs can restore aquifers and landscapes, manage water supplies to create and enhance livelihoods, and integrate roads with the landscape in ways that improve the climate resilience of infrastructure and maintain beneficial natural systems. Such programs create benefits that accumulate over time, paying long-term dividends to rural economies. The most ambitious among them will open up new economic opportunities and improve prospects for future generations. The Green Roads for Water concept is applicable to different geographies and climates. • In mountainous terrains Green Roads projects design road alignment and cross drainage to divert water to recharge aquifers in semiarid climates, provide low-cost and effective slope stabilization, and support preservation of ecosystems and national parks. • In arid and semiarid areas roads can be used to harvest water (van Steenbergen et al. 2018) to serve the communities around the road. The water intercepted by road bodies can be guided to recharge areas or surface storage or can be applied directly to the land. With the enormous lengths of roads being built, roads present the main opportunity for water harvesting and water buffer management in many semiarid areas (Salman et al. 2016). • In pastoral areas roads can contribute to management and productivity in several ways. The concentrated runoff from roads can support plantings of native grass species. Similarly, in very dry areas, road runoff can be used to rekindle the roots of useful tree species under farmer-managed natural revegetation programs. Under such programs, dormant tree shoots that come up after a sporadic watering event are systematically pruned, and local tree stands can be maintained in otherwise harsh environments. • In wet lowlands Green Roads for Water can help manage flooding and boost agricultural productivity. Roads in floodplains and coastal areas can play important roles in flood protection and agriculture given that they often double as embankments and provide evacuation routes and flood shelters. Roads and bridges also affect the shallow groundwater tables in low-lying areas and floodplains and can have enormous consequences for land productivity. The way in which a road is built, such as the height of bridge sills and culverts, will have considerable influence on the quality of the wetlands on either side of the road. • In desert areas Green Roads can be used to control sand dune movement or at least not aggravate it. Avoiding aligning the road with the prevailing wind direction limits the wind-tunnel effect that triggers sand motion. Roadside vegetation can also help stabilize newly opened areas. • Roads may also contribute to protection of wildlife areas. Wildlife movement is very much guided by the availability of water. The collection of runoff in designated storage within wildlife parks can support wildlife management and regreening of designated areas of the parks. Water runoff can also be directed to create buffers to curtail encroachment by livestock keepers or farmers.
