Response of Water Balance Components to Changes in Soil Use and Vegetation Cover Over Three Decades in the Eastern Amazon

Abstract

Impacts on global water resources may be intensifying due to the growing and differentiated forms of land use and occupation, which influence the water cycle and thus the maintenance of life. In the Amazon, the effect may be even worse, as it is one of the world's most vulnerable regions to these changes. This work aimed to analyze the response of the components of the water balance to changes in land use and cover in the Eastern Amazon over three decades (1980–2013). First, soil texture maps were prepared. These combined with the classes of use in each decade let us estimate the values of storage and variation in storage (ΔS) of water in the soil. The behavior of the components of the water balance [precipitation, potential evapotranspiration, actual evapotranspiration (E), and ΔS] were analyzed according to the Budyko model on the annual scale as a function of the aridity and evaporative indices. For the seasonal scale, a new parameter (y0) was introduced to explicitly represent the additional water available for E, in addition to instantaneous precipitation. The seasonality of the rains and the seasonal dynamics of storage were directly incorporated into the model developed, which allowed us to understand what the dominant control factors of water balance are. In the decade from 2000 to 2009, the remaining forest cover is only 48.91%, while the cover formed by pasture is 50.47%, meaning the water storage capacity in the soil decreased 8.1%. In the 1990s, to 1999, precipitation shows a reduction, probably as a reflection of the very strong events of La Niña and El Niño (1988–1989 and 1997–1998). Observing the sum of the surface area of water bodies in the region and the relationship of forest vs. pasture, it is possible to infer that the elevation in evapotranspiration is more related to the increase in evaporation due to the increase in the pasture area than to the reduction transpiration due to forest loss, reinforcing the hypothesis that evapotranspiration increases with pasture area.

Installation and calibration of sensors for analysis of soil humidity and temperature in eastern amazon areas

“…From the surface layers, water can be drained and percolated into deeper layers. Nevertheless, the basin lost 8.1% of its water retention capacity over three decades, that is, annual soil water storage changes in a watershed are water's balance important elements (Silva-Júnior et al, 2021). In addition, losses due to evapotranspiration occur, which are directly influenced by the type of vegetation, wind regime, air temperature, humidity, and incidence of solar radiation.…”

“…Thus, understanding and quantifying these soil variables are important for the formulation of means of managing hydrological resources and conflict resolution, especially in areas where access to water decreases during the dry season. This creates a contradictory idea, of a hydrological paradox, where the Amazonian environment, which is one of the largest springs on the planet, goes through droughts even with high rainfall and bodies of water, such as those of the Itacaiúnas River Basin (IRB), show intermittent behavior within their regimes and reduced storage capacity (Alves & Beserra Neta, 2018;Silva-Júnior et al, 2021).…”

A Stochastic Bayesian Artificial Intelligence Framework to Assess Climatological Water Balance under Missing Variables for Evapotranspiration Estimates

“…The water balance for a given region obeys the mass conservation principle summarized by Equation (5), which describes the equilibrium of water inflows and outflows from a control volume [41].…”

Using feature engineering and machine learning in FAO reference evapotranspiration estimation

“…To estimate the actual evapotranspiration in specific crops or landscapes, the potential evapotranspiration from a well-watered defined surface, known as reference evapotranspiration (ETo), is used. Computing reference evapotranspiration (ETo) is an essential step in the evaluation of the water balance in watersheds (Silva-Júnior et al, 2021), drought threat analysis, estimating crop water requirements (Mehta and Pandey, 2015), irrigation scheduling, and various other tasks in water resources management. The Food and Agriculture Organization (FAO) provides a widely used method for calculating ETo based on several meteorological variables, including temperature, humidity, wind speed, and solar radiation (Allen et al, 1998).…”