View source for Water-harvesting-of-road-runoff

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 <div class="title"><h3>5.69 -Water Harvesting of Road Runoff.</h3><br><h3 class="ch-owner">Alexandra Zwerenz , University of Guelph, Canada </h3></div>
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<p><b>Related video(s)</b>: Road runoff harvesting (Source: Access Agriculture)</p>
 <p><i> https://www.accessagriculture.org/slm04-road-runoff-harvesting?cat_id=1499</i></p>

<p>Suggested citation for this chapter.</p>
<p>Zwerenz,A. (2022) Water Harvesting of Road Runoff, In Farmpedia, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org</p>
       <h3 class="title-bg">Background and Overview</h3>
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          <p>Road Runoff Water Harvesting is a method of water harvesting from the rain that falls on roads near farms, and it can make a significant difference between hunger and a plentiful harvest, especially during drought seasons and in dry, desert areas (Rodgers, 2017) (Figure 1). A cost analysis showed high economic returns on investments in Road Runoff Water Harvesting (Hatibu et al., 2006). Compared to non-users, Road Runoff Water Harvesting resulted in an increase of USD 82 per capita income per season and 24% less poverty among its users (Gebru et al., 2020). Moreover, it is a practical strategy for mitigating flooding and enhancing climate-resilience in semi-arid areas, promoting improvement in crop yield and income for farmers (Gebru et al., 2020). Overall, road runoff water harvesting is considered as a sustainable approach to land management, as the method proves to be beneficial for both the land and the environment, particularly in a changing climate (Rodgers, 2017). Yet, this practice continues to be unvalued and ignored in the scientific community (Rodgers, 2017).  </p>
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<p>However, some local farmers have started to adopt the method through traditional practices, including some modern innovations, fostering the direct involvement of local creators and community leaders (Rodgers, 2017). Practices to conserve freshwater involve diverting runoff into farmlands through soil or stone water channels, small water storage ponds, terraces, and roadside pits (Gebru et al., 2020).</p>  

<p>One of the most commonly used techniques is floodwater spreaders along road surfaces, which will direct runoff water from the top of the road to farmland, adding moisture to the soil (Van Steenbergen et al., 2021).
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<p>Such spreaders, like the one shown in Figure 2, consist of shallow bend foundations (30 cm) and utilize local, easily accessible resources, making it a cost-effective method (Van Steenbergen et al., 2021). However, annual reconstruction is necessary (Van Steenbergen et al., 2021). Furthermore, road crossings can serve as structures for spreading water, allowing additional groundwater recharge (Van Steenbergen et al., 2021).</p>

<p>As demonstrated in Figure 3, water-spreading weirs can function as primary river crossings, diverting floods from dry riverbeds to surrounding areas. The floodwater is then spread through connecting roads linked to the weir/river crossing (Van Steenbergen et al., 2021). Additionally, water-spreading weirs are reinforced with drop structures and cross-drainage designed to provide stability (Van Steenbergen et al., 2021).</p>
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<p><i>Figure 3: Water spreading weirs.  https://documents1.worldbank.org/curated/en/102951623742853259/pdf/Green-Roads-for-Water-Guidelines-for-Road-Infrastructure-in-Support-of-Water-Management-and-Climate-Resilience.pdf</i></p>

<p>The second most common road runoff harvesting technique is called surface storage fed from road drainage which includes ponds, cisterns, and borrow pits (see Box 1.1) (Van Steenbergen et al., 2021). Such pits are typically located near the road and can be used as seepage ponds, water storage, and recharge (Van Steenbergen et al., 2021). This method requires more labour, as gravel, soil, and sand are needed (Van Steenbergen et al., 2021). Overall, both practices are feasible and realistic to complete in most cases (Gebru et al., 2020). This chapter examines the practices, benefits, and constraints of Road Runoff Water Harvesting to make it more accessible for small-scale farmers worldwide. 
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       <h3 class="title-bg">Details on how to practice road runoff water harvesting  </h3>
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<p>Box 1.1: (Van Steenbergen et al., 2021)</p>
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<p>As illustrated in Figure 4, the water harvesting technique with the greatest storage capabilities is the raised road embankments with raised culverts approach (Figure 4) (Van Steenbergen et al., 2021). This method, resembeling a dam-like structure, is adaptable to various environments, preserving water from running off and controlling its course. This promotes improved soil moisture, surface storage, and groundwater recharge (Van Steenbergen et al., 2021). The storage capacity depends on the height difference between the ground level and culverts of the road sections, relying on the function of the closed-in area (Van Steenbergen et al., 2021). Further, this approach mainly intends to improve wetlands and grazing areas (Van Steenbergen et al., 2021).</p>
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<p>Figure 5: Example of a dam made out of sand, collecting coarse sand upstream. https://roadsforwater.org/wp-content/uploads/2022/02/WB_Guidelines_final_publication.pdf</p>
<p>Embankments are especially useful in low-lying coastal areas, where ponds or canals can efficiently store water for dry seasons (Van Steenbergen et al., 2021). Excess sediment can be reused for road construction, road embankments, or water dams, to further flood prevention (Van Steenbergen et al., 2021).</p>
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<p>Figure 6: https://roadsforwater.org/wpcontent/uploads/2022/02/WB_Guidelines_final_publication.pdf
Layout of the best recommended practices for water harvesting (in coastal low land areas)</p>
<p>For the best outcome possible, the use of raised road embankments with raised culverts is recommended. Road and water coordination should be organized according to requirements before the road construction. For instance, the budget and labour required for road development varies depending on the measurements of the (flood) road embankments, including height, widths, and slopes (see Box 8.2 under Further Resources), and the needs of the specific location (raising of the road may be required) (Van Steenbergen et al., 2021). For farmland near a riverbed, turfing or vegetation of high-fibre crops can help prevent erosion on the side slope (Van Steenbergen et al., 2021). </p>
	<p>For water collection and storage, borrow pits can be reused; however, reprocessing must be addressed systematically, from planning and development to conversion and aftercare (Van Steenbergen et al., 2021). As the function of the pit will be affected by its size and shape, the availability of materials and resources is crucial. These materials include natural resources like clay loam, sandy loam, and sand, as well as tools for material extraction and the operation of dump trucks for potential relocation of material (Van Steenbergen et al., 2021). A 20-meter minimum neutral area is recommended for the construction (Van Steenbergen et al., 2021). The original pit should be accurately modified to fit the new needs for water storage but can be uneven in shape (the use of machinery may be required at this point depending on the size and future purpose of the pit) (Van Steenbergen et al., 2021). </p>
<p>In short, there are three main conditions for a functioning borrow pit: safety, stability, and shape. All those requirements can be achieved through the removal of potentially harmful sides or heaps, confirmation of a stable slope, and optimization of the storage capacities through the shape (Van Steenbergen et al., 2021). If the pit is unlined, a convex (rounded) shape is preferred (Van Steenbergen et al., 2021).</p>
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       <h3 class="title-bg">Benefits of Adopting Barley in Dry Conditions </h3>
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<p>There are many benefits for farmers who adopt barley to dry conditions. Highland barley has a high degree of cold tolerance, a short growing period, wide adaptability, early maturity, and high yield (Xie et al., 2023). Highland barley also has good nutritional value. It contains high levels of protein, vitamins, and fibre (Xie et al., 2023). The protein levels in barley are around 27.3%, with dietary fibre levels around 29%, and fat being at 4.57% (Zeng et al., 2018). Another benefit is dry extraction, which is a useful process for enriching certain nutrients in the barley grain. On top of this, it saves on resources like water and energy (Xie et al., 2023). Barley is also a good cover crop, that will preserve the nutrition and fertility of the soil. Barley can also act as a cover crop for other crops (Jacobs, 2016). Finally, excess barley grain can be sold commercially as a cash crop to make malt beer which is in high demand globally.</p>
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       <h3 class="title-bg">Benefits  </h3>
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<p>The advantages of Road Runoff Water Harvesting include its diverse functionality and suitability for all farmers located alongside all dirt tracks or tamarack roads (Rodgers, 2017). </p>
<p>During heavy rainfall, Road Runoff Water Harvesting approaches manage, conserve, collect and store runoff water, preventing soil sedimentation, flooding, and erosion of valuable farmland (Rodgers, 2017). Additionally, this method provides further water and hydration resources, which can be used for agricultural, domestic, and health purposes (Rodgers, 2017). 
The added filtration throughout the water collection process also benefits the overall water quality (Rodgers, 2017). Areas with heavy rainfall and extended dry seasons can implement water runoff collection approaches, including water storage reservoirs for irrigation and more. </p>
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       <h3 class="title-bg">Critical Analysis  </h3>
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<p>With so numerous benefits come various challenges to Road Runoff Water Harvesting at different locations. The complexity of the designs to achieve optimal results depends very much on the needs of the farmer and the location (Gebru et al., 2020). Due to such barriers, the adoption rate of road water harvesting practices is considerably low (Gebru et al., 2020). Further constraints include labour limitations, widely negative perceptions about the practices (lack of knowledge and communication), low levels of education among household heads, social capital, insufficient awareness among development practitioners and in the scientific world, not enough contact with development agents, and lastly, insecure land rights (Gebru et al., 2020).</p>
	<p>On the other side, as previously mentioned in the Introduction, a cost analysis showed high economic returns on investments in Road Runoff Water Harvesting (Hatibu et al., 2006). More stability is offered with this approach through the reduction of uncontrolled water loss, as well as the protection of fertile soil through the fewer risks of sedimentation (Van Steenbergen et al., 2021). Further, there are measurable improvements in groundwater levels throughout heavy rainfall seasons and dry seasons, enhancing the value of smallholder farms (Figure 4) (Van Steenbergen et al., 2021). </p>
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<p>Figure 7: https://roadsforwater.org/wp-content/uploads/2022/02/WB_Guidelines_final_publication.pdf
Measurable change and improvement of ground water recharge due to road water harvest practice 
implementations.</p>
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       <h3 class="title-bg">Further Information and Resources</h3>
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<p>1.Access Agriculture provides a brief and detailed demonstration of the different practices used for Road Runoff Water Harvesting: https://www.accessagriculture.org/slm04-road-runoff-harvesting. The video focuses on smallholder irrigation and rainwater harvesting using different approaches depending on your location (Rodgers, 2017).</p>  

<p>2.The World Bank Group summarized the Guidelines for Road Infrastructure in Support of Water Management and Climate Resilience in Green Roads for Water: https://roadsforwater.org/wp-content/uploads/2022/02/WB_Guidelines_final_publication.pdf. 
This resource includes a guide on how to calculate the right size for borrow pits and other ponds used for runoff water storage (Box 8.2).</p> 

<p>3.The United Nations fosters a global alliance for increased water security, including the agricultural sector, emphasizing the need for rainwater storage, and harvesting: https://sdgs.un.org/partnerships/global-alliance-improve-water-security-through-promoting-rainwater-harvesting-and.</p> 

<p>4.The Food and Agriculture Organizations of the United Nations (FAO) highlights and explains the benefits Road Runoff Water Harvesting has on crop yields: https://www.fao.org/3/br326e/br326e.pdf.</p> 
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       <h3 class="title-bg">References  </h3>
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<p>1.Food and Agriculture Organization of the United Nations (FAO). (2014). Compendium on 
Rainwater Harvesting for Agriculture in the Caribbean Sub-region – Concepts, calculations and definitions for small, rain-fed farm systems. Food and Agriculture Organization of the United Nations.  https://www.fao.org/3/br326e/br326e.pdf</p>

<p>2.Gebru KM, Woldearegay K, van Steenbergen F, Beyene A, Vera LF, Tesfay 
Gebreegziabher K, Alemayhu T. (2020). Adoption of Road Water Harvesting Practices and Their Impacts: Evidence from a Semi-Arid Region of Ethiopia. Sustainability. 12(21), 8914. https://doi.org/10.3390/su12218914</p>

<p>3.Hatibu N., Mutabazi K., Senkondo E.M., Msangi A.S.K. (2005). Economics of rainwater 
harvesting for crop enterprises in semi-arid areas of East Africa. Agricultural Water Management. 80, 74-86. https://www.sciencedirect.com/science/article/abs/pii/S0378377405002908 </p>

<p>4.Rodgers, J. (2017). SLM04 Road Runoff Harvesting. Access agriculture. Countrywise 
Communication, CIS Vrije Universiteit Amsterdam. https://www.accessagriculture.org/slm04-road-runoff-harvesting</p>

<p>5.United Nations. (n.d.). A global alliance to improve water security through promoting 
rainwater harvesting and storage for households, schools and health centres; for agriculture and ecosystems; and for urban climate resilience | Department of Economic and Social Affairs. United Nations. https://sdgs.un.org/partnerships/global-alliance-improve-water-security-through-promoting-rainwater-harvesting-and </p>

<p>6.Van Steenbergen, F., Arroyo-Arroyo, F., Rao, K., Alemayehu Hulluka, T., Woldearegay, K., Deligianni, A. 2021. Green Roads for 
Water: Guidelines for Road Infrastructure in Support of Water Management and 
Climate Resilience. International Development in Focus. Washington, DC: World 
Bank. doi:10.1596/978-1-4648-1677-2. License: Creative Commons Attribution 
CC BY 3.0 IGO. https://documents1.worldbank.org/curated/en/102951623742853259/pdf/Green-Roads-for-Water-Guidelines-for-Road-Infrastructure-in-Support-of-Water-Management-and-Climate-Resilience.pdf</p>