I studied a small mountainous catchment in Peru’s central Andean Amazon which provides ecosystem services such as potable water and hydropower-generated electricity to the rural town of Oxapampa, inhabited by 15,000 people. This area is within the recently designated UNESCO Biosphere Reserve Oxapampa-Asháninka-Yanesha. A National Park protects mostly pristine Tropical Montane Cloud Forests in the headwaters, above 2,400 meters above sea level. However, the lower forests outside the Park’s border are continuously converted to grazing and agricultural lands.
To what magnitude can this conversion affect the hydrological services that this catchment provides? To answer this question I focused on the interactions of soils with rainfall. I compared various hydraulic properties of soils across the three main land covers: forests, grazing and agricultural lands. The central aspect was to estimate the rates of water infiltration and transport (saturated hydraulic conductivity) in each land cover, and compare them against rainfall intensities. If the rainfall intensity exceeds the infiltration rate, overland flow is expected and can be modeled. If this process takes place, other processes can be inferred: increased erosion, decreased water quality, and less water storage in the subsurface for baseflow maintenance in the dry season.
To complement this information, I sampled soils to evaluate their degree of compaction and organic matter content. I am also monitoring soil moisture and soil temperature dynamics through the wet and dry season in the three land covers, using microclimatic automatic stations that collect data every 5 minutes. In addition, I monitored the baseflow in the main stream and interviewed the supply companies to estimate what percentage of water they use.
Why is this study important? Scientifically, we need to improve the understanding of hydrologic processes and the dynamics between people, forests and water in this under-researched ecosystem. In terms of climate change, expected warmer temperatures, shifts in the cloud condensation level, and higher rainfall intensities can further affect the hydrological services and vulnerability of people in this region. Therefore, information is needed for assessing adaptation measures. Finally, regarding conservation of these montane forests, there is a local initiative that is promoting an ecosystem services scheme for watershed management and conservation. Initiatives like this can only be successful if the services and activities that affect them are adequately quantified and monitored. Therefore this study provides insight for scientific, conservation, and local water management purposes.