Assessment of suitable observation conditions for a monthly operational remote sensing based crop monitoring system.

Abstract: Cloud cover is the main issue to consider when remote sensing images are used to identify, map and monitor croplands, especially over the summer season (October to March in Brazi). This paper aims at evaluating clear sky conditions over four Brazilian states (Sa?o Paulo, Parana?, Santa Catarina, and Rio Grande do Sul) to assess suitable observation conditions for a monthly basis operational crop monitoring system. Cloudiness was analyzed using MODIS Cloud Mask product (MOD35), which presents four labels for cloud cover status: cloudy, uncertainty, probably clear and confident clear. R software was used to compute average values of clear sky with a confidence interval of 95% for each month between July 1st, 2000 and June 30th, 2013. Results showed significant differences within and between the four tested states. Moreover, the period from November to March presented 50% less clear sky areas when compared to April to October

Cloud cover assessment for operational crop monitoring systems in tropical areas.

Abstract: The potential of optical remote sensing data to identify, map and monitor croplands is well recognized. However, clouds strongly limit the usefulness of optical imagery for these applications. This paper aims at assessing cloud cover conditions over four states in the tropical and sub-tropical Center-South region of Brazil to guide the development of an appropriate agricultural monitoring system based on Landsat-like imagery. Cloudiness was assessed during overlapping four months periods to match the typical length of crop cycles in the study area. The percentage of clear sky occurrence was computed from the 1 km resolution MODIS Cloud Mask product (MOD35) considering 14 years of data between July 2000 and June 2014. Results showed high seasonality of cloud occurrence within the crop year with strong variations across the study area. The maximum seasonality was observed for the two states in the northern part of the study area (i.e., the ones closer to the Equator line), which also presented the lowest averaged values (15%) of clear sky occurrence during the main (summer) cropping period (November to February). In these locations, optical data faces severe constraints for mapping summer crops. On the other hand, relatively favorable conditions were found in the southern part of the study region. In the South, clear sky values of around 45% were found and no signi?cant clear sky seasonality was observed. Results underpin the challenges to implement an operational crop monitoring system based solely on optical remote sensing imagery in tropical and sub-tropical regions, in particular if short-cycle crops have to be monitored during the cloudy summer months. To cope with cloudiness issues, we recommend the use of new systems with higher repetition rates such as Sentinel-2. For local studies, Unmanned Aircraft Vehicles(UAVs) might be used to augment the observing capability. Multi-sensor approaches combining optical and microwave data can be another option. In cases where wall-to-wall maps are not mandatory, statistical sampling approaches might also be a suitable alternative for obtaining useful crop area information

Usina hidrelétrica na amazônia e impactos socioeconômicos sobre os pescadores do município de Ferreira Gomes – Amapá

Socioeconomic impacts of the construction of the Ferreira Gomes Hydroelectric Power Plant (UHEFG) were analyzed in communities of fishermen affected before and after the filling of the reservoir. The study occurred between 2014 and 2015, in the municipality of Ferreira Gomes-AP. Data were collected using forms (Nsample=48) and a comparative analysis was performed to evaluate their significance (Mann-Whitney, p<0.05). The results showed that the Environmental Impact Assessment (EIA) did not adequately predict impacts in the fisheries sector. The comparative tests confirmed a) six variables with significant variation (p<0.05): monthly income, number of trips to fish, fishing difficulties, environmental conditions of the Araguari River, socioeconomic and environmental impacts; and b) a variable at the limit of significance (p≈0,056): fish trade. We concluded that the reparatory measures did not reestablish the socioenvironmental conditions, generating conflicts not foreseen.Os impactos socioeconômicos da construção da Usina Hidrelétrica de Ferreira Gomes (UHEFG) foram analisados ​​em comunidades de pescadores afetados antes e depois do enchimento do reservatório. O estudo ocorreu entre 2014 e 2015, no município de Ferreira Gomes-AP. Os dados foram coletados por meio de formulários (Nsample = 48) e uma análise comparativa foi realizada para avaliar sua significância (Mann-Whitney, p <0,05). Os resultados mostraram que o Estudo de Impacto Ambiental (EIA) não previu adequadamente os impactos no setor pesqueiro. Os testes comparativos confirmaram a) seis variáveis ​​com variação significativa (p <0,05): renda mensal, número de viagens para pescar, dificuldades de pesca, condições ambientais do rio Araguari, impactos socioeconômicos e ambientais; e b) uma variável no limite de significância (p≈0,056): comércio de pescado. Concluímos que as medidas reparatórias não restabeleceram as condições socioambientais, gerando conflitos não previstos