Forest Conversion to Pasture Affecting

¶ … forest conversion to pasture affecting the hydrological response of Amazon catchments? Signals in the Ji-Parana basin" by Rodriguez, Tomasella, and Linchares published on the 26th January 2010 in Wiley Interscience. It goes ahead to discuss in depth runoff. It is apparent to majority of us that the land use and vegetation cover over the land does not remain constant but constantly changes typically because of human activities and deforestation respectively. Deforestation on its own has the potential of affecting not only the forest/vegetation cover, but also hydrological response (Rodriguez, "is forest conversion to pasture affecting hydrological response"). Despite that many of vegetation changes are detectable in majority of small-catchment researches; it can however be difficult in large-scale studies. For this reason, at Ji-Parana basin in southwest Amazon, land use, land-cover changes, and stream flow fluctuations are examined combined with remotely sensed deforestation information to obtain viable results. Despite the Ji-Parana basin being large (

Rain falling on land has the potential of flowing either rapidly or slowly depending on the land cover as runoff and finally to streams. In addition depending on the soil characteristics of the area under consideration, infiltration varies where some of the water can percolate through the soil to greater depths and sometimes in to streams. The natural factors that influence infiltration rate include soil characteristics, plant and animals, and topography. Man can modify these features to highly influence runoff. For instance, areas with grass/vegetation will reduce runoff by reducing speed of water on surface hence increasing percolation chances. On the other hand, bare lands will offer less resistance to water hence faster runoffs. In the event that rainfall produces much water to the land surface than it can be absorbed by the soil, the excess water will be left on the surface to flow down slopes as runoff. Wet areas with higher vegetation covers can have higher water tables that lead to faster saturations hence runoff.

On soil characteristics, finer soils will reduce infiltration and increase runoff and vice versa. Still, the size of rain drops can help compact soil reducing runoff. Concerning plant cover, they increase infiltration rates in that they slow the pace of water falling to surface and reduce chances of faster runoff. Areas that lack vegetation are subject to flash floods whenever high precipitation takes place. In an incidence when there is a steep slop at headwaters, then more runoff is apparent. All this water will eventually reach the streams. If the runoff is much, it means much water will reach the streams hence higher chances of flooding, if runoff is less, less water reaches streams hence less potential for floods. Remember the rate of runoff is a factor of topography where steep slopes have faster flows compared to gradual slopes.