RESUMOO uso e a ocupação dos solos exercem influência marcante no escoamento superficial e aporte de sedimentos no leito dos mananciais, podendo alterar a qualidade e a disponibilidade da água. Com isto se objetivou com o presente trabalho, verificar a influência do uso e ocupação dos solos sobre os recursos hídricos do córrego Três Barras, município de Marinópolis, SP. Para constatar esta influência, realizou-se uma análise de correlação de Pearson entre os parâmetros de qualidade e disponibilidade de água e o uso e ocupação dos solos, cujos dados foram coletados entre 18/01/2006 a 10/12/2007. Concluiu-se que as áreas ocupadas por matas e pastagens (com menor intensidade) favoreceram a disponibilidade e a qualidade da água na Sub-Bacia. De maneira geral, as áreas habitadas, agricultadas e as matas degradadas, reduziram a disponibilidade e a qualidade da água da Sub-Bacia. ABSTRACTLand occupation and its use have a remarkable influence on the superficial water flow and the carrying of sediments to the riverbed and may change the quality and availability of water. The current study aimed to check the influence of the land occupation and use on the Três Barras stream resources, in Marinópolis, SP, Brazil. To check this influence, an analysis of Pearson´s correlation between the parameters of quality and availability and use of water and land was developed. The samples covered the period of January, 2006 until December, 2007. It may be concluded that areas occupied by forests and pastures (in less intensity) favoured the availability and quality of water of the watershed. The inhabited areas and those used for agriculture, and the degraded forests in general, reduced the availability and quality of water in the watershed.

Abstract:In the Brazilian semi-arid region, the intensification of agriculture results in a change of natural vegetation by irrigated crops. To quantify the contrast between these two ecosystems, the large-scale values of water productivity components were modelled in Petrolina (PE) and Juazeiro (BA) municipalities. The SAFER (Simple Algorithm For Evapotranspiration Retrieving) algorithm was used to acquire evapotranspiration (ET), while the Monteith's radiation model was applied for estimating the biomass production (BIO). Moderate Resolution Imaging Spectroradiometer (MODIS) satellite images were used together with agro-meteorological data. In Petrolina and Juazeiro, the mean monthly ET values for irrigated crops were 938 and 739 mm·month .Water productivity (WP) was analysed by the ratio of BIO to ET, defined here as the ratio of the net benefits from the mixed agricultural systems to the amount of water required for producing those benefits. The highest incremental WP values, as a result of the irrigated crops introduction, happened outside the rainy period. More spatial WP uniformity occurred in natural vegetation, when comparing with irrigated crops. The most frequent WP values in Petrolina were between 1.6 and 2.2 kg·m . The differences between the municipalities can be mainly explained by differences in precipitation and soil OPEN ACCESSRemote Sens. 2013, 5 5784 water storages conditions, promoting better rainfall use efficiency by the natural vegetation in the first one. The results of the current research are important for appraising the land use change impacts in situations of expanding irrigation areas.

WATER BALANCE A TOOL FOR PLANNING IN NORTHWAEST OF STATE OF SÃO PAULOKnowing the availability of the water on the soil for the future planning is the foundation for executing its rational use. Then, this project had as an objective to elaborate the monthly water balance for the region of Marinópolis, worthwest of the state of São Paulo. The water balance was determined using the Thorthwaite and Mather (1955) method, starting from the data obtained by Weather Station operated by the Hydraulics and Irrigation Division from UNESP Ilha Solteira. The year average precipitation is 1.111 mm and the potential evapotranspiration from 1.421 mm per year. Considering a Available Water Capacity (AWC) from 40 mm, the water balance resulted in eight months of water deficiency on the soil (april to november), with total accumulated of 490 mm and the surplus occurred in the months of december to march with 179 mm, concluding that it would be high rick with the cultivation without the use of systems of irrigation that must be projected to attend a demand between 3,9 and 4,6 mm per day.

The energy balance (EB) components were quantified in a commercial farm with corn crop, irrigated by central pivots, in the Northwestern side of São Paulo state, Southeast Brazil. The SAFER (Simple Algorithm For Evapotranspiration Retrieving) was applied to retrieve the latent heat flux (λE), considering six pivots, covering irrigated areas from 74 to 108 ha. With λE quantified and considering soil heat flux (G) as a fraction of net radiation (R n), the sensible heat flux (H) was acquired as a residual in the energy balance equation. Seven Landsat satellite images, covering all corn crop stages from 23 April 2010 to 29 August 2010, allowed relating the energy balance components according to the accumulated degree-days (DD ac) from the planting to harvest dates. The average R n values ranging from 5.2 to 7.2 MJ m-2 day-1 , represented 30 to 45% of global solar radiation (R G). Considering the variation of the energy balance components along the corn crop growing seasons, the average ranges for λE, H and G were respectively 0.0 to 6.4 MJ m-2 day-1 ,-1.5 to 6.7 MJ m-2 day-1 and 0.1 to 0.6 MJ m-2 day-1. The fraction of the available energy (R n-G) used as λE was from 0.0 to 1.3 indicated a good irrigation management, insuring that the water deficit could not be the reason of any yield reduction. Although R n did not reflected well the crop stages, its partition strongly depended on these stages. λE higher than R n and the negative H/R n , happened sometimes along the corn growing seasons. This occurred after the vegetative growth and before the harvest times, indicating heat advection from the surrounding areas to the irrigation pivots, which represented an additional energy source for the evaporative process. The models applied here with only the visible and infrared bands of the Landsat sensor are very useful for the energy balance analyses, considering the size of the corn crop irrigation pivots in Southeast Brazil, when subsidizing a rational irrigation water application in corn crop.

"Large-scale radiation and energy balances with Landsat 8 images and agrometeorological data in the Brazilian semiarid region,"