Multidecadal change in streamflow associated with anthropogenic disturbances in the tropical Andes

Abstract

Abstract. Andean headwater catchments are an important source of freshwater for downstream water users. However, few long-term studies exist on the relative importance of climate change and direct anthropogenic perturbations on flow regimes in these catchments. In this paper, we assess change in streamflow based on long time series of hydrometeorological data and land cover reconstructions in the Pangor catchment (282 km 2 ) located in the tropical Andes. Three main land cover change trajectories can be distinguished during the period 1963-2009: (1) expansion of agricultural land by an area equal to 14% of the catchment area (or 39 km 2 ) in 46 years' time, (2) deforestation of native forests by 11 % (or −31 km 2 ) corresponding to a mean rate of 67 ha yr −1 , and (3) afforestation with exotic species in recent years by about 5 % (or 15 km 2 ). Over the time period 1963-2009, about 50 % of the 64 km 2 of native forests was cleared and converted to agricultural land. Given the strong temporal variability of precipitation and streamflow data related to El Niño-Southern Oscillation, we use empirical mode decomposition techniques to detrend the time series. The long-term increasing trend in rainfall is remarkably different from the observed changes in streamflow, which exhibit a decreasing trend. Hence, observed changes in streamflow are not the result of long-term change in precipitation but very likely result from anthropogenic disturbances associated with land cover change.

Patterns in Soil Chemical Weathering Related to Topographic Gradients and Vegetation Structure in a High Andean Tropical Ecosystem

“…February to April is the most humid period with a monthly precipitation of slightly more than 100 mm, while July and August is the dry season with a monthly precipitation of about 35 mm. In addition to the rainfall, there is a continuous moisture input from clouds and fog in this high‐altitude páramo ecosystem (Molina et al, ). The mean annual air temperature is 8 °C with little seasonal variation.…”

Impacts of land use on the hydrological response of tropical Andean catchments

“…But diurnal temperature cycles are highly marked and can range between 0 and 20 °C (Buytaert et al, , ; Córdova et al, ). Luteyn (); Buytaert et al () and Molina et al () have reported annual precipitation amounts between 500 and 3000 mm year −1 , with an exceptionally high spatiotemporal variability (Buytaert et al, ; Célleri et al, ). In contrast, characterizing reference evapotranspiration has been limited by the scarce availability of meteorological data.…”

Multicriteria assessment of water dynamics reveals subcatchment variability in a seemingly homogeneous tropical cloud forest catchment

“…This is somehow surprising as research on the land use and land cover patterns effect on runoff is well documented at catchment (Chaves et al . , ; Coe, Latrubesse, Ferreira, & Amsler, ; Molina, Vanacker, Brisson, Mora, & Balthazar, ; Neill et al . , ; Ochoa‐Tocachi et al .…”

“…, ; Iñiguez–Armijos, Leiva, Frede, Hampel, & Breuer, ; Molina et al . , ; Ochoa‐Tocachi et al . , ; Tapia‐Armijos, Homeier, Espinosa, Leuschner, & de la Cruz, ), man‐made changes in natural land cover and land use have been identified as an emerging ecological problem.…”