FAO/UNDP MEX 74/003 / Technical Report / Prepared for the International Conference on Managing Saline Water for Irrigation, Lubbock, Texas, U.S.A. August 16-20, 1976. / FAO of United Nations Project, UAAAN/FC / Buenavista, Saltillo, Coahuila, 1976. / Note: Item states For Internal Use only. Online copy not available. / INTRODUCTION: More than 52% cultivable area of Mexico is classified as arid and semi-arid. Nearly half of this area, particularly in the Northern States is extremely arid and presents with some salinity, alkalinity and water logging problems. Ground water, when available for irrigation, is often saline or moderately saline-sodic. The soils of this region are calcareous and contain some salts and sodium. Soils also contain sub-surface horizon rich in carbonate and compact in nature, which may be 30-90 cms below the ground surface. Before planning a major irrigation system for crop production, provision of drainage and leaching of salts is often recommended for this region. The good quality water from underground source may rarely be available for leaching salts and when available pumping costs are prohibitively expensive. It has also been pointed out in the past that such lands could be used to harvest water. In fact, rudimentary water harvesting systems have been established by local people in some parts of this area. Thus, with the need for integral land use and water reclamation in mind, a multipurpose water use and water harvesting system was developed. The requirements of this system, among others, are: (1) To collect enough water for multiple use inside or outside the system, (2) To increase the desired production of the marginal saline land within the system, and, (3) To provide an economically feasible long term farming system for the low-income community. Such system is under development at the Ejido San Francisco del Barrial, near Parras in the State of Coahuila.

No description available.

Two sites located near Ketama in the Morocco Rif have been selected, on the basis of limiting climatic factors, in order to study the relationship between tree rings and climate. After the trend associated with biological factors related to increasing age has been removed and all variables have been standardized, some statistical parameters have been computed and a variance analysis has been performed. After the persistence has been eliminated, an original technique of multiple regression on the principal components and of selection of the most significant variables has been built. Twenty -four climatic variables have been used. The principal aim of this paper is to describe this original statistical technique of data analysis and to illustrate its power with dendroclimatological data in Morocco. For the temperate site located in low altitude (1280 m), among the most important variables, we have retained total monthly precipitation for August, mean temperature of January, April, and May of the current year and mean temperature of October of the previous year. For the cold site (2100 m), total monthly precipitation for September and temperatures of January and May of the current year and precipitation for October of the previous year definitely influence the growth rate of cedars.

Dendrochronological research on Juniperus polycarpos growing in west and central Iran reveals that the radial growth in this species depends mainly on the amount of precipitation in the more arid regions. When the amount of rain is sufficient, i.e. above 450 mm, the prevailing summer temperature seems to become the limiting factor. Favorable conditions which prevailed during the periods 1685-1695 and 1790-1800 resulted in better width growth, while less favorable conditions which prevailed during the years 1725-1735 and 1855-1865 resulted in narrow rings.

The aim of this research is to assess various options for the management of topsoil stockpiles on disturbed lands and to evaluate the viability and germinability over time of the seedbanks in these stockpiles for use in rehabilitation. To predict their success, experimental trials were designed and conducted.

The aim of this research is to assess various options for the management of topsoil stockpiles on disturbed lands and to evaluate the viability and germinability over time of the seedbanks in these stockpiles for use in rehabilitation. To predict their success, experimental trials were designed and conducted.

La difficulté à comprendre la désertification dans les zones arides tunisiennes se manifeste dans les interactions complexes entre les dynamiques socioéconomiques et biophysiques à différentes échelles spatiales et temporelles. L’apport de ce travail réside tant dans les avancées sur la compréhension des causes et processus, que dans la proposition d’approches systémiques (climat-homme-espace-ressources : système CHER), géographiques (paysage) et multi-acteurs, associées à des méthodes (modèles et outils) reproductibles, pour l’évaluation et le suivi (indicateurs) des risques de désertification, en lien avec leurs déterminants interactifs, à une échelle territoriale. Le paysage, en tant que source d’information et instrument, est au cœur de ce travail. Ce dernier a conduit à i) la construction des modèles explicatifs CHER déclinés par type paysager (issue d’une lecture multidisciplinaire et de la caractérisation des paysages), ii) l’élaboration des indices de risque de désertification (par intégration spatiale des fonctionnements biophysiques et socioéconomiques et à travers la modélisation), iii) la compréhension et la comparaison entre types paysagers des risques et de la part respective prise par les causes socioéconomiques et biophysiques, et iv) la proposition de trois nouvelles approches/méthodes/outils visant à mieux évaluer les actions de lutte déjà mises en œuvre, cibler les futures actions et suivre la désertification. Les résultats ont tous été élaborés dans l’interdisciplinarité et avec la mobilisation des acteurs/décideurs de la gestion durable des territoires pour augmenter leur utilité dans les programmes de lutte contre la désertification, pour valoriser les observatoires de l’environnement et leur donner un rôle d’appui aux politiques publiques. / The difficulty in understanding desertification in the Tunisian arid zones manifested in the complex interactions between socioeconomic and biophysical dynamics at different spatial and temporal scales. This work contribute on advanced understanding of the causes and processes and propose a systemic (climate-human-space-resource: CHER), geographical (landscape) and multi-actors approaches associated with methods (models and tools) reproducible for the assessment and monitoring (indicators) of risk of desertification, according to its interactive determinants on a territory scale. The landscape, as a source of information and the tool, is at the core of this work which led to i) the construction of explanatory models broken down by type of landscape (based on multidisciplinary characterization of landscapes), ii) the development of indexes of desertification risk (based on spatial integration of biophysical and socio-economic functioning through modeling), iii) the understanding and comparison of risks and their respective causes in the landscape types, and iv) the proposal of three new approaches / methods / tools to better assess the actions already implemented to combat desertification, to better target future actions and to better monitor desertification. The results have all been developed in interdisciplinarity and involve the mobilization of actors / decision makers in the sustainable management of territories to increase their usefulness in programs to combat desertification, to value environmental observatories and give them a role to support public policies.