Modelling the impact of recent land‐cover changes on the stream flows in northeastern Puerto Rico

Abstract

Abstract:We investigated the influence of recent and future land-cover changes on stream flow of a watershed northeastern Puerto Rico using hydrological modeling and simulation analysis. Monthly and average annual stream flows were compared between an agricultural period (1973)(1974)(1975)(1976)(1977)(1978)(1979)(1980) and an urbanized/reforested period (1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995) using the revised Generalized Watershed Loading Function model. Our validated results show that a smaller proportion of rainfall became stream flows in the urbanized/forested period compared with the agricultural period, apparently because of reforestation. Sensitivity analysis of the model showed that evapotranspiration, precipitation, and curve number were the most significant factors influencing stream flow. Simulations of projected land-cover scenarios indicate that annual stream flows would increase by 9Ð6% in a total urbanization scenario, decrease by 3Ð6% in a total reforestation scenario, and decrease by 1Ð1% if both reforestation and urbanization continue at their current rates to 2020. An imposed hurricane event that was similar in scale to the largest recent event on the three land-cover scenarios would increase the daily stream flow by 62Ð1%, 68Ð4% and 67Ð1% respectively. Owing to the environmental setting of eastern Puerto Rico, where sea breezes caused by temperature differences between land surface and the ocean dominate the local climate, we suggest that managing local land-cover changes can have important consequences for water management.

The impact of forest regeneration on streamflow in 12 mesoscale humid tropical catchments

“…The change covers the start of the record (cf. Wu et al (2007) reported a change in Q tot of −25 % (corrected for changes in P using a single P station that was not included in the current study as it did not meet the necessary quality requirements), between 1973-1980 and 1988-1995 for the Río Fajardo catchment in north-eastern Puerto Rico (here identified as catchment H). Wu et al (2007) attributed this negative change in Q to the small amount of forest regeneration occurring during that period (estimated at 8 % based on the interpolated time series shown in Fig.…”

“…8). Thus, Wu et al (2007) may have overestimated the reduction in Q tot for the Río Fajardo catchment because they only used part of the available record. Additionally, given that the Río Fajardo catchment appears to be an outlier in the present analysis (Fig.…”

Effects of intensive agriculture in the structure and functioning of tropical headwater streams

“…Streams located in non-forest catchments displays instable flow and high nutrient inputs (WU et al, 2007;CARLSON et al, 2014), turning these ecosystems heterogeneous and as a consequence, opening space for the development of species with different niche occupying and exploration (SIMPSON, 1949). Oppositely, forested streams exhibit a higher number of environmental filters for stream algae development, e. g. light deprivation due to canopy cover and low nutrients due to riparian forest buffers, which are the main resources for algal development (STEVENSON et al, 1996).…”

“…The flow dynamics of a stream are controlled mainly by the distribution and amount of rainfall, the catchment relief, and land use characteristics in the catchment ESHLEMAN 2004;MACEDO et al, 2013;STANFIELD;JACKSON, 2011). In the tropics, the massive and ongoing conversion of forests to other land uses such as agriculture and urbanization are altering flow regimes (CARLSON et al, 2014;WU et al, 2007) and changing stream characteristics (Table 1).…”

“…It is well established that some of the main problems related to flow regime modifications are due to human land-use activities and poor landscape management, such as dam construction and agricultural water abstraction, both in temperate regions BUNN;ARTHINGTON, 2002;DUDGEON et al, 2006;POFF et al, 1997;POWER et al, 1996) and in the tropics (CHAVES et al, 2008;GERMER et al, 2009;WU et al, 2007).…”