Rubens Sonsol Gondim

Estimativa da Et o pelo modelo Penman-Monteith FAO com dados mínimos integrada a um Sistema de Informação Geográfica 1

O objetivo do presente trabalho foi avaliar a metodologia de estimativa da EtoPM utilizando dados minimos integrados a um Sistema de Informacao Geografica, na bacia do Jaguaribe, Ceara. Foi utilizado o sistema integrado de modelagem regional PRECIS (Providing Regional Climates for Impacts Studies), versao 1.2, utilizando as condicoes de contorno do Modelo Climatico Global, HadAM3P, acoplado ao Modelo Climatico Regional (HadRM3P), atraves da tecnica dinâmica de reducao de escala (downscaling). Dados mensais de temperaturas maxima e minima e precipitacao foram gerados para o periodo de 1961-1990, os quais foram analisados quanto a sua variabilidade espacial (latitude/longitude), utilizando-se geoestatistica (krigagem). Para validacao, foi aplicada regressao linear entre EtoPM estimada com dados minimos e estimada com dados medidos atraves de uma estacao meteorologica de referencia. A media da EtoPM anual estimada com dados minimos situou-se em 1.719 mm. A metodologia funcionou satisfatoriamente na regiao estudada, considerando-se os resultados da regressao (coeficiente angular de 0,95, coeficiente de determinacao de 0,902, residuos menores que 0,45 mm dia-1 e Raiz do Quadrado Medio do Erro (RQME) igual a 0,067 mm dia-1).

Mudanças climáticas e impactos na necessidade hídrica das culturas perenes na Bacia do Jaguaribe, no Estado do Ceará

The aim of this study was to estimate climate change impacts on irrigation water demand for permanent crops. The PRECIS (Providing Regional Climates for Impact Studies) system was applied, and downscaling techniques were used at the river basin level, with the boundary conditions of the regional climate model (HadRM3P). A climate data set was generated for 1961 to 1990 (baseline) and for future climate projections. The regional geographical coordinates were considered for interpolation in a georeferenced coordinated system. The reference evapotranspiration was estimated through data of monthly average temperature. Projected climate change increased projected irrigation water demand, because evapotranspiration was estimated to increase by 3.1 to 2.2% and rainfall was estimated to decrease by 30.9 to 37.3%. The 2040 water need was estimated to increase by 32.9% to 43.9%, according to the analyzed scenario.

ASPECTOS PRODUTIVOS DA MELANCIEIRA SOB IRRIGAÇÃO COM DÉFICIT E DIFERENTES COBERTURAS UTILIZANDO O MODELO ISAREG

The objective of this work was to assess the pulp resistance, soluble solids and yield of watermelon fruits grown under different irrigation managements (determined by the ISAREG model) and mulches, and their interactions. After a survey carried out on local producers, two experiments were conducted, using a completely randomized block design in split-plot arrangement with four replications, in the Teaching, Research and Extension Unit (UEPE) of the Federal Institute of Ceara (IFCE), Jaguaribe-Apodi Irrigation District (DIJA), State of Ceara, Brazil. The treatments consisted of four irrigation managements in the plots, M1 (100% of the available-water capacity (AWC) of the soil), M2 (80%), M3 (60%) and M4 (average water depth used by local producers) and four mulch types in the sub-plots, without mulching (C0) with rice husk (C1), white plastic (C2) and black plastic (C3) as mulches. The results were subjected to analysis of variance, and significant results were subjected to regression (irrigation managements), average test (mulches) and trend graphs (interaction between the factors). The irrigation management practiced during the watermelon crop cycle by the local producers of the Irrigation District of Jaguaribe-Apodi (DIJA) in the State of Ceara, Brazil, is not appropriated, since they usually apply more water than the highest water depth determined by the ISAREG model (100% of the AWC). The plants grown under irrigation water depth of 365.20 mm (M1) and soils with mulches of rice husk or white plastic had the highest yields and fruits with better quality of soluble solids and pulp resistance.

Climate change impacts on water demand and availability using CMIP5 models in the Jaguaribe basin, semi-arid Brazil

The objective of this study was to analyze climate change impacts on irrigation water demand and availability in the Jaguaribe River basin, Brazil. For northeastern Brazil, five global circulation models were selected using a rainfall seasonal evaluation screening technique from the Intergovernmental Panel on Climate Change named Coupled Model Intercomparison Project Phase 5. The climate variables were generated for the base period of 1971–2000, as were projections for the 2025–2055 future time slice. Removal of maximum and minimum temperature and rainfall output bias was used to estimate reference evapotranspiration, irrigation water needs, and river flow using the rainfall—river flow hydrological model Soil Moisture Accounting Procedure for the baseline and future climate (Representative Concentration Pathways 4.5 and 8.5 scenarios). In addition, by applying improved irrigation efficiency, a scenario was evaluated in comparison with field observed performance. The water-deficit index was used as a water availability performance indicator. Future climate projections by all five models resulted in increases in future reference evapotranspiration (2.3–6.3%) and irrigation water needs (2.8–16.7%) for all scenarios. Regarding rainfall projections, both positive (4.8–12.5%) and negative (− 2.3 to − 15.2%) signals were observed. Most models and scenarios project that annual river flow will decrease. Lower future water availability was detected by the less positive water-deficit index. Improved irrigation efficiency is a key measure for the adaptation to higher future levels of water demand, as climate change impacts could be compensated by gains in irrigation efficiency (water demand changes varying from − 1.7 to − 35.2%).