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Palustrine carbonates are frequently found with active and dried karstic springs in the foothills of the mountains bordering the Persepolis Basin, southwest Iran. A combination of geological conditions favours their formation, including (i) the presence of karstic limestone aquifers in the limbs of anticlines cut through by fault systems; (ii) very gentle slopes from the spring resurgence point towards the centre of the alluvial plain, creating a flat waterlogged area; and (iii) a semiarid climate with marked precipitation seasonality or significant fluctuations in water discharge and wetland water table. We suggest the term 'anastomosing wetlands' or 'anastomosing palustrine environments' to denote the studied karstic spring-fed carbonate wetlands, because of similarities with anastomosing river systems in aerial view. The common presence of extended anastomosing wetland carbonatesin the Persepolis Basin and adjacent basins in the central and southern Zagros suggests that they can play an important role in the geological records of collision-related basin-and-range settings dominated by karstic limestones. Karstic spring wetlands are a main source of fresh water hosting a rich biodiversity, which attracts human communities, whose impact is visible in the archaeological material imbedded in the wetland stratigraphy. Fresh water availability, through these spring wetlands, partly explains why the semiarid Persepolis region was selected by successive civilizations, from Elamites to Persians until early Islamic entities, to establish regional centres throughout the period from the third millennium B.C. to the first millennium A.D. Only a few of these ecosystems have survived the intensive human activities of recent decades. Des carbonates palustres sont frequemment associes a des sources karstiques actives et assechees dans le contrefort des montagnes bordant le bassin de Persepolis, dans le sud-ouest de l'Iran. Une combinaison de conditions geologiques favorise leur formation, a savoir: i) la presence d'aquiferes de calcaires karstiques dans les flans d'anticlinaux decoupes par des systemes de failles, ii) les pentes tres douces des points de resurgence de sources vers le centre de la plaine alluviale, creant une zone plane saturee et iii) un climat semi-aride caracterise par une saisonnalite marquee des precipitations ou d'importantes fluctuations de l'ecoulement de l'eau et de la nappe phreatique dans les zones humides. Nous proposons le terme << zones humides anastomosees >> ou << milieux palustres anastomoses >> pour designer les zones humides a carbonates karstiques alimentees par des sources en raison de similitudes qu'elles presentent en vue aerienne avec des reseaux hydrographiques anastomoses. La presence repandue de carbonates dans les zones humides anastomosees du bassin de Persepolis et des bassins voisins des parties centrales et sud des monts Zagros indiquerait qu'ils peuvent jouer un role important dans les profils geologiques des milieux de bassins et montagnes. Ces milieux sont associes a des collisions tectoniques dans lesquels predominent des calcaires karstiques. Les zones humides karstiques alimentees par des sources constituent une source d'eau douce majeure abritant une grande diversite biologique qui attire les collectivites humaines, dont l'impact est visible dans le materiel archeologique present dans la stratig-raphie des zones humides. La disponibilite d'eau douce qu'offrent ces zones humides alimentees par des sources explique en partie pourquoi la region semi-aride de Persepolis a ete retenue par des civilisations successives, des Elamites aux Perses jusqu'aux premieres entites islamiques, pour y etablir des centres regionaux durant toute la periode allant du 3e] millenaire avant notre ere au 1er millenaire de notre ere. Seuls quelques-uns de ces ecosystemes ont survecu a l'intense activite humaine des recentes decennies. [Traduit par la Redaction], Introduction Palustrine carbonates are continental carbonates deposited in marginal shallow lake environments or wetland systems, later modified by subaerial exposure and pedogenic processes (Alonso-Zarza 2003; Alonso-Zarza and Wright 2009a). They [...]

Objective karstification assessment is a key component of hydrogeological studies of aquifers. In this research, surface and subsurface karst development have been assessed, based on different methods, to get insights into karstification processes in the area of the Cheshme-Ali karstic aquifer, located in northeast Iran. GIS information, remote sensing, and field measurements of fracture density and frequency have been used to determine surface karst development. The monthly spring discharge rate and physicochemical parameters of the Cheshmeh-Ali Spring in 2003-2004 were used to determine subsurface karstification rate. Additional monthly measurements of discharge rate and chemical parameters were carried out in 2010-2011. The evaluation of surface karstification (Sk) illustrates moderate karstification of 51.47 percent. The response of the aquifer to precipitation shows the impact of one or more conduits in the water level fluctuation zone that generate a rapid response of the spring to large precipitation events. The spring hydrograph analysis indicates a pseudo-diffuse flow system in the region. The hydrograph and chemograph analyses demonstrate average subsurface karstification index of 1.7 m. Finally, it is concluded that although both methods demonstrate karstification processes in an aquifer, these kind of reservoirs still require more intelligible approaches, as well as comparable methods for their description. [ABSTRACT FROM AUTHOR]

An aquifer test is used mostly to determine the storage coefficient and transmissivity. Although residual drawdown data are widely used in estimating the transmissivity of aquifers, the estimation of storage coefficients with recovery data is controversial. Some researchers have proposed methods to estimate storage coefficients with recovery data by assuming equality of storage coefficients for the recovery and pumping periods ( S = S′). The aim of this study is to determine storage coefficients without such an assumption, that is, S≠S′. The method is a modified version of Banton-Bangoy's method without considering drawdown data due to pumping. Drawdown is plotted vs. the logarithmic ratio ( t′/ t) or time since pumping stopped to the duration of pumping and the ratio of storage coefficient during recovery to the storage coefficient from the pumping period ( S′/ S). The method is verified with one case study and two synthetic examples. Thus, it is possible to determine storage coefficient of pumping period accurately without any data from pumping period by recovery data. [ABSTRACT FROM AUTHOR]