Community-based adaptation strategies are essential for dealing with drought in the Peruvian Andes, according to a new study by Ralph Lasage et al. published in Sustainability.
Over 80% of residents in the Peruvian Andes rely on agriculture as a major source of income and are highly dependent on the availability of water resources. But in the past, droughts associated with El Nino events have been devastating for these communities and led to increased migration from rural areas to cities. According to Ralph Lasage and a team of researchers from VU University Amsterdam and Amsterdam University College, the drought of 1982 resulted in 60% – 70% reduction in highland agricultural production.
And water availability in the Andes is set to continue to decline as glaciers recede. Effective water management systems and adaptation measures on the local scale play significant roles in reducing the impacts of climate change on the glaciers thousands of people rely on, Lasage and his team found.
When glaciers melt, the risk of outburst floods increases dramatically. In 1941, the glacial lake Palcacocha in the Peruvian Andes burst and tons of water crashed into the city of Huaraz, killing around 5,000 people. In the following decade, two more glacial lake outburst floods (GLOFs) occurred in the Cordillera Blanca in north-central Peru due to excessive water released when glacier moraine dams failed. To address the issue, the Peruvian government strengthened terminal moraine dams, sophisticated valve systems, and drain pipes to prevent extensive damage when future GLOFs occurs. In addition, it initiated glaciological unit, which helped prevent many outburst floods and significant fatalities.
However, outburst flooding is not the only glacier melt-related issue that concerns Peruvians. Droughts associated with climate variability, which threaten the country’s water supply, pose a major concern for residents of the South American nation. Shrinking glacier volume during this century is projected to intensify. But hydrological data gaps limit scientists’ ability to understand cycles of flooding and droughts. it is difficult for them to assess vulnerability to floods and droughts on regional level.
Through their study, Lasage and his team presented a stepwise participatory approach to create a vulnerability index and develop community-based adaptation measures. The study was conducted in the Chorunga catchment, which is “representative of the environmental and socio-economic conditions of farming communities across the Andes”. They found that improving the efficiency of water usage and storage was a bigger challenge for communities than creating water storage at high elevations close to glaciers.
The Chorunga catchment, which is part of the Ocona River basin, is a poor rural area where roughly “68% of the population live in poverty, compared with 14% for the whole of Peru”. Located in the south of the Cordillera Blanca, the Chorunga catchment received the majority of its water irrigation comes from the Coropuna Glacier, which lost 37% of its total volume and has been rapidly retreating, in the form of melting glacier water. In addition, the team conducted in-depth study of the functioning of the villages’ irrigation systems and the governance of water resources. Perceived vulnerability was evaluated alongside a variety of socio-economic characteristics of the respondents, including income, education, access to water, and etc.
Lasage and his team started by gathering information on local households’ perception of their vulnerability to droughts and the effectiveness of proposed adaptation strategies through questionnaires and face-to-face interview in the Chorunga catchment. The vulnerability index was defined as the product of “exposure” (or frequency of drought periods) and “sensitivity” (or perceived impacts of a drought on people’s livelihoods) divided by “response efficacy” (or perceived effectiveness of adaption measures in response to reduced water availability). In addition, the team gathered information on the governance of water resources as well as irrigation systems through in-depth interviews with government offices, NGOs, and local colleges. More importantly, the team collaborated with a variety of Peruvian stakeholders (e.g. local farmers, Water Associations, Irrigation Commissions, and etc.) and initiated several possible adaption measures. Ultimately, some adaption measures were selected on the basis of climate projections and investment costs.
Glacier recession has been accelerating since the 1970s, which will likely lead to the disappearance of the glaciers. As a result of rising temperatures, a large portion of the precipitation comes in the form of rainfall instead of snow. Therefore, water availability is anticipated to decline during growing season for crops on the long run even though increased melting glacier water will slightly contribute to water runoff in the short term. In other words, additional melt-water from glacier retreat will not make a difference in increasing discharge, because the effect of reduced precipitation due to high temperatures will most likely be overwhelming.
The vulnerability analysis reveals that households with a larger area of irrigated land tends to be less vulnerable to droughts; households with lower income are more vulnerable but less willing to adapt to climate change; and people with a higher education appear to be less sensitive to drought and willing to cope with adaptation measures. There is a strong correlation between households’ water availability and their vulnerability to droughts.
The selected adaptation measures concentrated on improving the efficacy of water usage and storage in the Chorunga catchment. In particular, surface dams were constructed to store rainfall during the wet season, and to be used during the dry season. Low-cost gravity drip irrigation systems and water-efficient crops were introduced to maximize crop production in the fields with limited amount of water. In addition, roof-water harvesting systems were installed to increase useable water. Generally speaking, the implementation of such adaptation measures will possibly increase households’ water availability during the dry season, and hence reduce their vulnerability to droughts.
“The stepwise approach proved to be suitable to structure the process of developing and implementing adaptation measures jointly with a wide range of stakeholders in a rural area in Peru. It enabled the inclusion of information ranging from the local to the global scale and led to the joint implementation of several community-based measures”, said Lasage et al.