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This chapter is concerned with the hydrological resources in the dry forest of Guanacaste, northwest of Costa Rica. It describes the hydrological region of Guanacaste, including the estuarine, littoral, and terrestrial systems and watersheds that are connected by the fluvial system. It then analyzes the ecological importance of stream corridors and the human impact on the environment. It also offers recommendations for safeguarding hydrological resources and their associated biodiversity in Guanacaste.

This chapter highlights human modification of fluvial channel systems in the past. It also looks at other research efforts on archaeological excavation, place-name investigation, and historical study based on documentary or cartographic evidence. This chapter also explains the limitations of the geomorphological concepts and approaches to determining the degree and timing of past human channel modification. Two distinct approaches to fluvial geomorphology include theoretical and empirical approaches. In the theoretical approach, predictions of the flow of water and its effect on sediment are constructed from relatively simple hydrological equations such as the Raleigh equation or Stokes Law, while the empirical approach focuses on studies of landform distribution patterns.

This chapter describes the hydraulic volatility and seasonal inundation as elements of geomorphologic process in the case of Orissa Delta, which, in the pre-colonial era, appears to have been harnessed by the local populace rather than sought to be undermined. That is, cultivators in pre-colonial eastern India seemed to have evolved a tradition of flood utilization and dependence. The ecological integrity of the Orissa Delta does not refer to some original pristine pre-colonial state of being, but is measured instead by the latitude the fluvial system was allowed as a geomorphologic process: wherein the fluvial action of erosion and deposition lead to the consolidation of the delta as a land form. Colonial administrative deliberations provide some of the most cogent and careful observations on the relationships between inundations and agrarian production in the delta. Flood dependence as agrarian practice appeared to be able to sustain itself without fundamentally unsettling the equation between hydraulic volatility and geomorphologic process.

This chapter introduces the themes and arguments of the book. In particular, it explains the benefits of adopting a holistic approach to the history of the river basin that acknowledges its cultural, physical, and biological unity. Treating the Tigris and Euphrates as a continuous whole brings to light the magnitude and significance of river flow that fostered contacts between upstream and downstream regions. Beyond facilitating communication, the twin rivers formed the backbone of the early modern Ottoman economy in the region by supporting complementary subsistence strategies, such as irrigation agriculture, animal husbandry, and wetland exploitation. In addition to the themes and arguments, this chapter offers a brief introduction to the history of the Ottoman Empire and the ecology of the Tigris-Euphrates basin.

Abiotic factors are the primary reason for the differentiation of deserts from other ecosystems. Fundamentally, it is the low rainfall that deserts experience that differentiate them from other habitats. Rainfall in deserts tends to fall in pulses, which can vary considerably in their magnitude and timing. An important change in rainfall that affects many deserts is the El Niño-Southern Oscillation effect that is associated with the unusually large warming of the ocean. Many deserts have very high spatial variation in geological substrates and, consequently, soil type. Saline soils are rather common in deserts. Stone substrates usually have relatively level gravel surfaces known as desert pavement. Rock desert landscapes normally have bare rock surfaces, with a huge pavement kept clear of sand and gravel by the wind. Fire is not considered as an important factor in desert ecosystems because fuel loads (created primarily by grasses) are generally too low.