María Cintia Piccolo

Estimating soil moisture and the relationship with crop yield using surface temperature and vegetation index

Abstract Soil moisture availability affects rainfed crop yield. Therefore, the development of methods for pre-harvest yield prediction is essential for the food security. A study was carried out to estimate regional crop yield using the Temperature Vegetation Dryness Index (TVDI). Triangular scatters from land surface temperature (LST) and enhanced vegetation index (EVI) space from MODIS (Moderate Resolution Imaging Spectroradiometer) were utilized to obtain TVDI and to estimate soil moisture availability. Then soybean and wheat crops yield was estimated on four agro-climatic zones of Argentine Pampas. TVDI showed a strong correlation with soil moisture measurements, with R 2 values ranged from 0.61 to 0.83 and also it was in agreement with spatial pattern of soil moisture. Moreover, results showed that TVDI data can be used effectively to predict crop yield on the Argentine Pampas. Depending on the agro-climatic zone, R 2 values ranged from 0.68 to 0.79 for soybean crop and 0.76 to 0.81 for wheat. The RMSE values were 366 and 380xa0kgxa0ha −1 for soybean and they varied between 300 and 550xa0kgxa0ha −1 in the case of wheat crop. When expressed as percentages of actual yield, the RMSE values ranged from 12% to 13% for soybean and 14% to 22% for wheat. The bias values indicated that the obtained models underestimated soybean and wheat yield. Accurate crop grain yield forecast using the developed regression models was achieved one to three months before harvest. In many cases the results were better than others obtained using only a vegetation index, showing the aptitude of surface temperature and vegetation index combination to reflect the crop water condition. Finally, the analysis of a wide range of soil moisture availability allowed us to develop a generalized model of crop yield and dryness index relationship which could be applicable in other regions and crops at regional scale.

Shallow lakes from the Central Plains of Argentina: an overview and worldwide comparative analysis of their basic limnological features

The Central Plains of Argentina is a heterogeneous environment, but the lakes there share some fundamental features: they are all shallow and polymictic as being well exposed to wind. First, we provide a synthesis of the climate, geology, and hydrological network. We also discussed shallow lakes origin and their limnological and biological salient features. Second, we focus on Pampean shallow lakes from a global perspective, comparing the limnological variables: total phosphorus concentration (TP), total nitrogen concentration (TN), chlorophyll a (Chl a) concentrations, and Secchi disk reading (SD) from a compiled database. No significant differences in the Chl a vs. TP relationship were found between Pampean and other shallow lakes. Otherwise, the chlorophyll yield per unit of phosphorus of Pampean lakes is similar to the world shallow lakes average. Moreover, the relationship SD vs. Chl a differed significantly between Pampean and the remaining world lakes, about 50–60%. When confronted against other lakes worldwide, Pampean shallow lakes depart from most of them as having higher TP, TN, and Chl a concentrations and much lower SD transparency, and therefore they stand as extremes of the trophic-state continuum. Despite their highly turbid state, these lakes provide valuable ecosystem services that are highly appreciated and mobilize important economic resources.

Hazard, vulnerability and coastal erosion risk assessment in Necochea Municipality, Buenos Aires Province, Argentina

This contribution determines the coastal erosion risk of Necochea and Quequén cities, Necochea Municipality, Buenos Aires Province (Argentina). Both risk components, hazard and vulnerability, were assessed by the construction of indices. The hazard index is composed of four indicators: the erosion or accretion rate, coastal geomorphology, storm waves effects, and sediment supply. The vulnerability index is comprised of land use/cover, demographic, life conditions, and work and consumption indicators, and includes population census data such as demographic, education, health, sanitary, economic, production, work and population exposure aspects. The analysis concluded that coastal erosion risk ranges from very low to high along the study area, Quequén yielding the highest values. Risk levels vary in both cities based on the uneven spatial distribution of hazard. The risk assessment developed herein constitutes a practical and adequate tool that can be utilized with other elements and tasks in the elaboration of a coastal management program.

Estimation of ecosystem metabolism from diel oxygen technique in a saline shallow lake: La Salada (Argentina)

AbstractStudies based on continuous monitoring of diel changes in dissolved oxygen concentration allow the estimation of ecosystem nmetabolism and provide a measure of the overall trophic processes of an ecosystem. In this study, net ecosystem production (NEP), community/ecosystem respiration (R), and gross primary production (GPP) rates were estimated in relation to physicochemical and climatic variables for 18xa0months in La Salada, a saline shallow lake. Net autotrophic conditions prevailed during the study period (NEP: 64.05xa0±xa044.22xa0mmolxa0O2xa0m−2xa0day−1). GPP and R were positively correlated and were synchronized on a daily timescale, with GPP typically greater than R. Principal component analysis revealed that monthly rates of GPP, R, and NEP responded, as expected, to temperature and light seasonal patterns. Water level and conductivity fluctuations, because of evapoconcentration and water management, were relevant as a driver of the physicochemical and biological characteristics of the lake. In saline lakes as La Salada, an adequate management of water resources will be relevant to maintain the ecosystem equilibrium and the quality of its resources.

Short and medium-term coastal evolution of Necochea Municipality, Buenos Aires province, Argentina

The short and medium-term coastal evolution of Necochea Municipality, Buenos Aires province (Argentina) was studied. The medium-term evolution study was based on aerial photographs from 1967 and 1984, and satellite images from 2004, using the dune or cliff toe as coastline indicator. The short-term evolution was studied from February 2006 to December 2009 by means of seasonal beach profiles and sediment sampling. Results showed that in the medium-term at Necochea, the coastline has remained stable or has advanced. Whereas in the short-term, the analysis has evidenced incipient erosion processes. On the other hand, at Quequén the retreat of the coastline and the negative sedimentary balances (medium and short-term) are clearly indicating an accentuated erosion process. The different degrees of coastal erosion are related in part to beach vulnerability to wave storms but mainly to anthropogenic actions, which have affected the beach sediment supply. These results evidence the necessity to develop a coastal management programme.

Crecimiento urbano y cambios del uso/ cobertura del suelo en las ciudades de Necochea y Quequén, Buenos Aires, Argentina

Urbanization is a territorial and socioeconomic process that induces a radical transformation of land/use cover. It produces great changes in the environment and therefore, is the principal cause of environmental problems and risks. Based on aerial photographs and satellital images, urban growth dynamics and land/use cover change were evaluated at the coastal urban area of Necochea municipality (Argentina). Between 1967 and 2004, urban land/cover use increased from 21,95 to 28,44 % while non urban land/cover use descended. Population growth excedeed urban expansion rate, estimating that the densifi cation of urban occupation is notably higher than the urban sprawl growth.

Geomorphometric assessment of drainage systems in a semi-arid region of Argentina using geospatial tools and multivariate statistics

In semi-arid environments there is often a lack of data on hydrological variables that limits the ability to understand key hydrological processes. In response to this need, geomorphometric analysis is a quantitative approach that has proven to be useful. This work aims to assess and classify 35 exorheic drainage basins located in a semi-arid area of Argentina (Northeastern Patagonia) according to their geomorphometric properties by using GIS technology and principal component (PCA) and cluster analysis (CA) multivariate techniques. In addition, an assessment of automated drainage network extraction accuracy was performed by comparing it with the actual drainage network. The study showed that it was possible to derive automated drainage networks with errors lower than 6xa0%. By comparing both PCA and CA, it was found that the former allows a good understanding of the clustering of basins from the CA. All basins were clustered into four groups following a significant spatial continuity. This type of study gives the basis for regional-scale analysis, and provides further information for subsequent modeling.

Study of the surface water circulation in San Blas channel (Argentina) using landsat imagery

This paper deals with the application of satellite images to study turbidity and water circulation patterns in San Blas channel during a theoretical tidal cycle. Eight Landsat TM and ETM images acquired under clear-sky conditions and representing different tidal stages were selected from a pool of Landsat images provided by the argentinean National Commission of Space Activities (CONAE) and the US Geological Survey. Standard digital image processing techniques were used to perform geometric and radiometric corrections on the visible and near-infrared bands. An image-based atmospheric correction (COST method by CHAVEZ, 1996) was applied. An ISODATA unsupervised classification was performed in order to identify different turbidity levels throughout the channel and adjacent areas. The results suggest that suspended sediment transport towards the channel mouth by ebb currents occurs along both flanks. These currents carry suspended sediment into the open sea, generating an ebb tidal delta which tends to rotate in a clockwise direction. Flood currents trigger turbidity mostly over the southern flank of the channel, generating a flood tidal delta with elongated banks extending in the direction of the tidal currents. From the elongated shape of the turbidity plumes, general tidal circulation patterns were identified.

Estudio comparativo de tres modelos climáticos en Argentina

The lack of meteorological data, with a long time series in some areas all over the world, generate difficulties when we have to characterize the climate. In this context, climate models are relevant to obtain these type of data. Particularly, in Argentina there are no meteorological stations that are distributed equidistantly with records over fifty years, therefore it climatic characterization is complicated. In this context, the aim of this study was to set for Argentina the climatic model that best represent the following variables: precipitation, relative humidity, mean, minimum and maximum temperature. To carry it out, historical meteorological data (from Servicio Meteorologico Nacional) registered In Situ and those who belong to three climatic models (Reanalysis NCEP/NCAR, WorldClima and NEW01) were analyzed for the period 1950-2010. For comparison, different statistical techniques were applied (Analysis of the variance, Fisher tests, regression analysis, correlation coefficients, determination and consistency). In addition, interpolation methods were applied in order to analyze the spatial distribution of each meteorological variable. As a result, climatic models are useful to characterize the climate in those areas with lack of information. Wordlclim has the best fit for mean temperature, while NEW01 for precipitation.

Propuesta sostenible para mitigar los efectos climáticos adversos en una ciudad costera de Argentina

Los indicadores de sostenibilidad climatica constituyen herramientas fundamentales para complementar las politicas de ordenamiento del territorio urbano y pueden beneficiar la calidad de vida sus habitantes. En el presente trabajo se diseno un indicador climatico urbano para la ciudad de Bahia Blanca considerando variables meteorologicas y analisis de la percepcion social. El mismo permitio delimitar la ciudad en cuatro regiones bien diferenciadas entre si. A partir de entonces, se realizo una propuesta sostenible para mitigar los efectos adversos del clima a partir de la aplicacion del metodo DPSIR. Las mismas estuvieron destinadas a mejorar las condiciones de vida de la poblacion. Los resultados permitieron considerar que una pronta implementacion de la misma junto con una activa participacion de los actores sociales y los tomadores de decisiones es necesaria para mejorar las condiciones actuales en la que se encuentra la ciudad. Con las medidas propuestas, la poblacion local sabra como actuar ante la ocurrencia de distintos eventos extremos, eventos de desconfort climatico, etc. Al ser un metodo sencillo, la metodologia aplicada en este estudio puede replicarse en otras ciudades del mundo con el objetivo de mejorar la calidad de vida de los habitantes.