Análisis del efecto de los mercados de agua sobre el beneficio de las explotaciones, la contaminación por nitratos y el empleo eventual agrario

Abstract

The evidence available about the external effects of functioning water markets is ambiguous. While some authors have shown that water exchanges diminishes the polluting effects of irrigated agriculture, others conclude otherwise. The joint use of contaminant input taxes and the establishment of water markets gives rise to ambiguous results, because water and fertilisers are not substitutes. The objective of this paper is to examine the joint effects of establishing an hypothetical spot water market among farmers and a nitrogen tax on irrigators’ benefits, nitrogen pollution and hired external labour. Two non-linear models are formulated and developed that simulate irrigators’ behaviour and the functioning of inter-district water markets in the Guadalquivir basin. Results show that water markets would increase hired farm labour and irrigators’ surplus, though at the cost of increasing nitrates pollution. The reduction of nitrates contamination achieved by the tax is attenuated as a result of water exchanges, which in turn contribute to reduce the negative income effects caused by the nitrates tax. Water markets increase unambiguously the social benefits resulting from increasing hired labour.

Efectos económicos regionales de las transferencias de agua: el papel de la mobilidad de los factores en el caso del sector agrícola de Baleares

“…0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 0,00 % Variation Water Table 2 reveals that, regardless of the level of factor mobility, most transfers are made for the cultivation of green vegetables, the crop with the highest shadow price. This result is coherent with those obtained in other studies in Spain and elsewhere [for instance, Vergara (1996), Rosegrant et al (1995), Calatrava and Garrido (2001), Arriaza et al (2002) and Diao et al (2005)]. Flowers constitute another crop for which water would be bought in the market, irrespective of the degree of factor mobility.…”

“…However, in the context of a long run drought (Table 4), production of rainfed crops is strongly affected by the water market creation, which causes an almost generalized fall in production. The only exception is green vegetables, which turn out to be one of the rainfed crops with higher added value [Calatrava and Garrido (2001), Martínez and Gómez-Limón (2004)]. …”

“…Furthermore, water transfers might have a positive effect in agricultural employment as shown by Calatrava and Garrido (2001) using a non-linear mathematical programming model to simulate a water market in the Guadalquivir basin (Spain). In the same line, using a multi-criteria programming model applied to the Duero Valley (Spain), Martínez and Gómez-Limón (2004) show how water transfers can reduce the negative effect of droughts on agricultural employment by between 20% and 45%.…”

El valor del uso del agua en el regadío de la cuenca del Segura y en las zonas regables del trasvase Tajo-Segura

“…Se trata de una metodología que ha sido aplicada por numerosos autores, siendo con diferencia la más extendida y utilizada, y existiendo numerosas aplicaciones a nivel nacional desde trabajos como el de Varela-Ortega et al (1998). Sirvan como ejemplo los trabajos de Albiac et al (2006Albiac et al ( , 2008, Arriaza et al (2002; Calatrava y Garrido (2001, 2005, Garrido (2000), Gómez-Limón y Riesgo (2004), Gómez-Limón y Martínez (2006), Iglesias et al (2003), Iglesias y Blanco (2004) y Riesgo y Gómez-Limón (2005.…”

“…A nivel nacional, el Grupo de Estudios Econó-micos del Ministerio de Medio Ambiente realizó una estimación del Margen Neto medio por m 3 de agua en todas las comarcas españolas (Maestu y Gómez, 2008), mientras que el estudio de Gil et al (2009) aborda el análisis econométrico de la productividad del uso agrario del agua por provincias. Muchos de los trabajos existentes a nivel nacional estiman funciones de demanda del agua para zonas regables con el objeto de analizar el impacto de políticas tarifarias o de mercados de agua (Albiac et al, 2006(Albiac et al, y 2008Arriaza et al, 2002Arriaza et al, y 2003Ballestero et al, 2002;Garrido, 2000;Calatrava y Garrido, 2001, 2005Gómez-Limón y Martínez, 2006; Gómez-Limón y Riesgo, 2004;Riesgo y Gómez-Limón, 2005). Otros trabajos realizan estimaciones puntuales de la productividad aparente o del valor medio del agua de riego (Colino y Martínez-Paz, 2007;Maeztu y Gómez, 2008;Berbel et al, 2011).…”