Seasonal Predictability of Daily Rainfall Characteristics in Central Northern Chile for Dry-Land Management

The seasonal predictability of daily winter rainfall characteristics relevant to dry-land management was investigated in the Coquimbo region of central northern Chile, with focus on the seasonal rainfall total, daily rainfall frequency, and mean daily rainfall intensity on wet days at the station scale. Three approaches of increasing complexity were tested. First, an index of the simultaneous El Nino–Southern Oscillation (ENSO) was regressed onto May–August (MJJA) observed precipitation; this explained 32% of station-averaged rainfall-amount variability, but performed poorly in a forecasting setting. The second approach used retrospective seasonal forecasts made with three general circulation models (GCMs) to produce downscaled seasonal rainfall statistics by means of canonical correlation analysis (CCA). In the third approach, a nonhomogeneous hidden Markov model (nHMM) driven by the GCM’s seasonal forecasts was used to model stochastic daily rainfall sequences. While the CCA is used as a downscaling method for the seasonal rainfall characteristics themselves, the nHMM has the ability to simulate a large ensemble of daily rainfall sequences at each station from which the rainfall statistics were calculated. Similar cross-validated skill estimates were obtained using both the CCA and nHMM, with the highest correlations with observations found for seasonal rainfall amount and rainfall frequency (up to 0.9 at individual stations). These findings were interpreted using analyses of observed rainfall spatial coherence, and by means of synoptic rainfall states derived from the HMM. The downscaled hindcasts were then tailored to meteorological drought prediction, using the standardized precipitation index (SPI) based on seasonal values, the frequency of substantial rainfall days (>15 mm; FREQ15) and the daily accumulated precipitation deficit. Deterministic hindcasts of SPI showed high hit rates, with high ranked probability skill score for probabilistic hindcasts of FREQ15 obtained via the nHMM

Funções de pedotransferência relacionadas à variabilidade espacial da retenção de água em solos de várzea

The estimation of non available soil variables through the knowledge of other related measured variables can be achieved through pedotransfer functions (PTF) mainly saving time and reducing cost. Great differences among soils, however, can yield non desirable results when applying this method. This study discusses the application of developed PTFs by several authors using a variety of soils of different characteristics, to evaluate soil water contents of two Brazilian lowland soils. Comparisons are made between PTF evaluated data and field measured data, using statistical and geostatistical tools, like mean error, root mean square error, semivariogram, cross-validation, and regression coefficient. The eight tested PTFs to evaluate gravimetric soil water contents (Ug) at the tensions of 33 kPa and 1,500 kPa presented a tendency to overestimate Ug 33 kPa and underestimate Ug1,500 kPa. The PTFs were ranked according to their performance and also with respect to their potential in describing the structure of the spatial variability of the set of measured values. Although none of the PTFs have changed the distribution pattern of the data, all resulted in mean and variance statistically different from those observed for all measured values. The PTFs that presented the best predictive values of Ug33 kPa and Ug1,500 kPa were not the same that had the best performance to reproduce the structure of spatial variability of these variables.A estimativa de variáveis do solo não disponíveis, por meio do conhecimento de outras variáveis medidas, pode ser obtida com o uso de funções de pedotransferência (FPT) com economia de tempo e custos. Entretanto, havendo grande diferença entre os solos, o uso desse método pode conduzir a resultados indesejáveis. Neste estudo é discutida a aplicação de FPTs desenvolvidas por alguns autores usando solos de diferentes características, para avaliar a retenção de água em dois solos de várzea brasileiros. As comparações foram feitas entre os dados medidos e estimados pelas FPTs, usando ferramentas estatísticas e da geoestatística, como erro médio, raiz quadrada do erro médio, semivariogramas, validação cruzada e coeficiente de regressão. As oito FPTs testadas para avaliar o conteúdo gravimétrico de água no solo (Ug) sob as tensões de 33 e 1.500 kPa apresentaram tendência em superestimar Ug 33 kPa e em subestimar Ug 1.500 kPa. As FPTs foram classificadas de acordo com seu desempenho e também em relação ao seu potencial em descrever a estrutura de variabilidade espacial do conjunto de dados medidos. Embora nenhuma das FPTs tenha alterado o padrão de distribuição dos dados, todas resultaram em média e variância estatisticamente diferentes daquelas verificadas para o conjunto dos valores medidos. As FPTs com melhor capacidade preditiva dos valores de Ug33 kPa e Ug1.500 kPa não foram as mesmas que tiveram o melhor desempenho para reproduzir a estrutura de variabilidade espacial dessas variáveis.ICTP (Trieste-Italy)Ghent University (Ghent-Belgium)CNPqCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)EMBRAPA - Clima Temperad

The contribution of the European Society for Soil Conservation (ESSC) to scientific knowledge, education and sustainability

Soil is an integral component of the global environmental system which supports the quality and diversity of terrestrial life on Earth. Therefore, it is vital to consider the processes and impacts of soil degradation on society, especially on the provision of environmental goods and services, including food security and climate change mitigation and adaptation. Scientific societies devoted to soil science play significant roles in reducing soil degradation and promoting soil conservation by advancing scientific knowledge, education and environmental sustainability. The ESSC was founded on 4 November 1988, with the aims to: 1. Support research on soil degradation, soil protection and soil and water conservation. 2. Provide a network for the exchange of knowledge about soil degradation processes and soil conservation research and practises. 3. Produce publications on major issues relating to soil degradation and soil and water conservation. 4. Advise regulators and policy-makers on soil issues, especially soil degradation, protection and conservation. The societal challenges that can be addressed through better soil protection, advancing knowledge and scientific approaches to soil protection and sustainable management, mean the ESSC embraces the on-going development, application, review and constructive criticism of highly innovative scientific soil conservation methods. In this context, the ESSC analyses and publicizes the roles and functions of soil in natural and human-modified systems and the functional optimization of soils to ensure sustainable environmental protection. “The thin layer of soil that forms a patchy covering over the continents controls our own existence and that of every other animal of the land” (Rachel Carson (1962) in ‘Silent Spring’).European Society for Soil Conservatio