Adaptation of water resources systems to changing society and environment: a statement by the International Association of Hydrological Sciences

ABSTRACT

We explore how to address the challenges of adaptation of water resources systems under changing conditions by supporting flexible, resilient and low-regret solutions, coupled with on-going monitoring and evaluation. This will require improved understanding of the linkages between biophysical and social aspects in order to better anticipate the possible future co-evolution of water systems and society. We also present a call to enhance the dialogue and foster the actions of governments, the international scientific community, research funding agencies and additional stakeholders in order to develop effective solutions to support water resources systems adaptation. Finally, we call the scientific community to a renewed and unified effort to deliver an innovative message to stakeholders. Water science is essential to resolve the water crisis, but the effectiveness of solutions depends, inter alia, on the capability of scientists to deliver a new, coherent and technical vision for the future development of water systems.

EDITOR D. Koutsoyiannis; ASSOCIATE EDITOR not assigned     

Ein Lateritprofil auf klastischen Sedimenten des Mittelmiozäns von Neyveli (Madrasstate — Indien)

Zusammenfassung Mittelmiozäne Deltasedimente aus kaolinitischen Quarzsanden, in die sich Kaolinitlagen, Lignit-Linsen und Lateritoidhorizonte einschalten, werden als Aufarbeitungsdetritus des praemiozän lateritisierten Grundgebirges gedeutet. An ihrer Oberfläche befindet sich ein postmittelmiozäner Laterithorizont. Unter Auflösung von Quarz und Zerstörung eines Teiles der Schwerminerale und Tonminerale wurden Eisen-Konkretionen, Kaolinit und Spuren von AI-Hydroxiden und -Oxidhydraten neu gebildet.Diese hier ausgebildete Delta-Fazies — Verknüpfung von lateritischem Umlagerungsschutt mit autochthonen Lateritisierungsvorgängen — kann verglichen werden mit den Bauxiteinschaltungen in klastische Coastal-plain-Serien von Guiana und Queensland und schließlich mit Sidérolitique- und Wealdenfazies.Als ähnliche klastische Serie ist die Tambo Group der Cape York-Halbinsel in Queensland, die nach Evens (1959) ins Tertiär gestellt wird, zu betrachten. Durch Lateritisierung und Bauxitisierung der kaolinitischen Sandsteine (Loughnan u. Bayliss, 1961) bildeten sich hier die wichtigsten derartigen Verwitterungslagerstätten der Welt.Zahlreiche ähnliche Sedimentserien — vorwiegend aus dem Tertiär (Sidérolitique), aber auch aus der Unterkreide (Wealden) und dem Karbon (Millstone grit. Schottlands) werden von Millot (1964, p. 170–183) in dem Kapitel Faciès sidérolitique sehr anschaulich geschildert.

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Middle miocene deltaic sediments forming kaolinitic quartz sands with intercalations of kaolinitic clay layers, lignite lenses and lateritoid horizons are interpreted as reworked detritus of premiocene lateritic soils on the cristallin basement. On top of this series a lateritic horizon of post middle miocene age is developped. The neoformation of iron concretions, kaolinite and traces of Al- hydroxides and -oxidhydrates is accompanied by solution of quartz and destruction of heavy minerals and clay minerals.This deltaic facies — demonstrating a combination of reworked lateritic detritus with autochthonous lateritic soil formation is compared with bauxite intercalations in clastic coastal plain series of Guiana and Queensland and last not least with Sidérolithique and Wealden facies.

     

Zur Petrographie der Bauxitlagerstätten auf der „Charnockite-suite“ im Salemdistrikt und in den Nilgiri-Hills,Südindien

Three profils of fossil Bauxites probably of Early Tertiary age in the Shevaroy Hills and in the Nilgiri Hills, South India, are examined. They are formed by isovolumetric transformation of charnockites under conservation of relict structures. The chemical and mineralogical composition of the bauxites depends on the petrology of the source rock. Na, K, Ca, Mg and the main quantity of silica are extracted, Al and Fe have been enriched relatively and in certain places even absolutely. The mineral transformation in the beginning of the weathering developped in two phases:

1. Leaching and precipitation within the cleavage pattern of the minerals,
2. Leaching and precipitation in the places of the former mineral relicts.

Different later phases of weathering produced Fe- and Al-rich solutions, which are precipitated in the intervals of porous rocks.     

Electron spin resonance of stabilized free radicals in sedimentary organic matter

Electron spin resonance (ESR) is evaluated as a method to study the thermal degradation of sedimentary organic matter which consists mainly of kerogen. Whole rock and separated kerogen samples were pyrolysed stepwise (ambient to 700°C at 50°C increments), extracted and analysed for elemental composition and ESR spectra at each step. Whole rock samples give rise to complex spectra which include those of paramagnetic metals and are therefore unsuitable in most cases for this purpose.The ESR parameters g value, ΔH and N_g differ for different types of immature organic matter. An increase in N_g,shift of g value to 2.0026–2.0028 and reduction in h are the main trends during pyrolysis and in natural heating of sedimentary organic matter.The peak generations of liquid and gaseous hydrocarbons coincide with maxima of free radical density. ESR spectroscopy in combination with complementary geochemical characterization of the sedimentary organic matter can serve to indicate maturity with respect to peak oil-gas generation.     

Partitioning of elements between majorite garnet and melt and implications for petrogenesis of komatiite

Partitioning of elements between majorite garnet and ultrabasic melt has been studied at 16 GPa and 1950° C. Ca, Ti, La, Sm, Gd, Zr, Hf, Fe, Ni, Mn, K, and Na are enriched in the melt, whereas Al, Cr, V, Sc and Yb are concentrated in majorite garnet. Thus, majorite garnet fractionation by partial melting could produce chemical heterogeneities in these elements deviating from chondritic abundance. Using the partitioning behaviour of elements between majorite garnet and ultrabasic melt, the petrogenesis of komatiite is discussed. A simple model to explain the chemical varieties of komatiites is as follows. Aluminadepleted komatiite was generated by partial melting of the primitive mantle at 200–650 km depth, and alumina-enriched komatiite is the product of remelting of the residual solid at the same depths, whereas alumina-undepleted komatiite was formed by partial melting of the primitive upper mantle at depths shallower than 200 km. We suggest the possibility of large-scale chemical layering or heterogeneity in the early Archean upper mantle as an alternative model for komatiite genesis; shallower mantle depleted in majorite garnet and the underlying mantle enriched in majorite garnet. Alumina-depleted and alumina-enriched komatiites in the early Archean might be generated by a high degree of partial melting of the layered mantle. Such chemical layering could have been homogenized by the late Archean. This explains the observations that alumina-depleted and alumina-enriched komatiites were generally formed in the early Archean but alumina-undepleted komatiite was erupted in the late Archean.     

Low frequency electrical impedance of partially molten gabbro: The effect of melt geometry on electrical properties

Electrical impedance of partially molten gabbro was measured as a function of the frequency of the applied electric field. The impedance of the partially molten gabbro was mainly controlled by the volume and geometry of partial melt, which were observed with an optical microscope study of the quenched sample. The experimental results are interpreted by a theory that formulates the electrical property of rocks containing partial melt, taking ionic diffusion in the melt into account. The theory evaluates the contributions from two types of melt-geometry distributed in the rock matrix, namely:

1. (a) nearly isolated melt pockets, and

2. (b) connected melt along grain boundaries.

According to the theory, connected melt mainly contributes to the increase of net conductivity, while melt pockets increase displacement current and cause the frequency dependence of impedance. The characteristic ionic diffusivity in melt pockets was determined from the peak frequency of the imaginary part of impedance. The magnitude of diffusion coefficient is estimated to be of the order of 10⁻⁷ to 10⁻⁶ cm²/sec. This suggests that sodium, iron, magnesium and/or calcium ions mainly carry the electric charge in partial melt. The observed frequency dependence of impedance is considered to reflect ionic polarization in melt pockets due to the migration of these alkali ions toward solid-melt interfaces.The present experimental and theoretical work suggests that electrical properties of the earth's upper mantle may involve an intrinsic frequency dependence associated with ionic diffusion in the frequency range of geomagnetic observation, if a partial melt zone exists. The analysis of the earth's conductivity structure may be inadequate if such intrinsic frequency dependence of mantle media is neglected.     

Porosity in chalk – roles of elastic strain and plastic strain

Chalks originate as Cretaceous to Recent pelagic or hemipelagic calcareous ooze, which indurate via burial diagenesis to chalk and limestone. Because they accumulate in pelagic settings with high environmental continuity, chalks may form thick formations and even groups. For this reason, and because chalks have a simple mineralogy (low magnesium calcite, silica and clays), they are ideal for the study of diagenetic processes including the depth-related decrease of porosity. It is the aim of this study to illustrate how the evaluation of in situ elastic strain can help in understanding these processes including the interplay between stress-controlled diagenetic processes and processes furthered by thermal energy. Petrophysical core and well data can be used for analyses of how porosity reduction via pore collapse and pressure dissolution is related to in situ elastic strain. The data in question are: depth, density of overburden, pore pressure, ultrasonic P-wave velocity and dry density/porosity. The analysis reveals that the transition from ooze to chalk is associated with high elastic strain and consequent pressure dissolution at calcite–particle contacts causing contact cementation. The transition from chalk to limestone is also associated with high elastic strain, especially at clay–calcite interphases causing development of stylolites via pressure dissolution, and consequent pore-filling cementation. Following each transformation the elastic strain drops rapidly. The observation of this diagenesis-related pattern in elastic strain of the sedimentary rock is novel and should not only be helpful in understanding the porosity development in sedimentary basins, but also add basic scientific insight.     

Recent and historical tsunami deposits from Lake Tokotan,eastern Hokkaido,Japan, inferred from nondestructive,grain size,and radioactive cesium analyses

Geological evidence of recent tsunamis from sediment samples collected from Lake Tokotan, a coastal lagoon in eastern Hokkaido, northern Japan, was detected using computed tomography (CT) and soft X-ray images, grain size, and radionuclide profiles. Initial field observations revealed that sediments had no discernable sedimentary structures at the top of the core. However, results of CT imaging, soft X-ray, and grain size analyses show evidence for three invisible sand layers that are intercalated with mud layers. These sand layers exhibit trends of landward fining and thinning. Furthermore, the distribution of sand layers was limited to the center and seaward parts of the lake. Vertical profiles of cesium and lead concentrations in combination with recent eyewitness accounts indicated that these sand layers are correlated with the 1973 Nemuro-oki, 1960 Chilean, and 1952 Tokachi-oki tsunami events. The deeper part of the sediment cores includes three volcanic ash layers and three prehistoric coarse sand layers. The prehistoric layers are correlated with unusually large tsunamis that were geologically identified in previous studies from eastern Hokkaido. These findings suggest that nondestructive techniques, in combination with radionuclide analysis, allow for detection of frequent but faint tsunami deposits. This technique allows for an improved understanding of the history of tsunami inundation in Lake Tokotan and of other locations for which stratigraphic evidence for faint tsunamis layers is not readily apparent from field assessments.

     

Automated classifications of topography from DEMs by an unsupervised nested-means algorithm and a three-part geometric signature

An iterative procedure that implements the classification of continuous topography as a problem in digital image-processing automatically divides an area into categories of surface form; three taxonomic criteria–slope gradient, local convexity, and surface texture–are calculated from a square-grid digital elevation model (DEM). The sequence of programmed operations combines twofold-partitioned maps of the three variables converted to greyscale images, using the mean of each variable as the dividing threshold. To subdivide increasingly subtle topography, grid cells sloping at less than mean gradient of the input DEM are classified by designating mean values of successively lower-sloping subsets of the study area (nested means) as taxonomic thresholds, thereby increasing the number of output categories from the minimum 8 to 12 or 16. Program output is exemplified by 16 topographic types for the world at 1-km spatial resolution (SRTM30 data), the Japanese Islands at 270 m, and part of Hokkaido at 55 m. Because the procedure is unsupervised and reflects frequency distributions of the input variables rather than pre-set criteria, the resulting classes are undefined and must be calibrated empirically by subsequent analysis. Maps of the example classifications reflect physiographic regions, geological structure, and landform as well as slope materials and processes; fine-textured terrain categories tend to correlate with erosional topography or older surfaces, coarse-textured classes with areas of little dissection. In Japan the resulting classes approximate landform types mapped from airphoto analysis, while in the Americas they create map patterns resembling Hammond's terrain types or surface-form classes; SRTM30 output for the United States compares favorably with Fenneman's physical divisions. Experiments are suggested for further developing the method; the Arc/Info AML and the map of terrain classes for the world are available as online downloads.     

Obliquity variations of terrestrial planets in habitable zones

We have investigated obliquity variations of possible terrestrial planets in habitable zones (HZs) perturbed by a giant planet(s) in extrasolar planetary systems. All the extrasolar planets so far discovered are inferred to be jovian-type gas giants. However, terrestrial planets could also exist in extrasolar planetary systems. In order for life, in particular for land-based life, to evolve and survive on a possible terrestrial planet in an HZ, small obliquity variations of the planet may be required in addition to its orbital stability, because large obliquity variations would cause significant climate change. It is known that large obliquity variations are caused by spin-orbit resonances where the precession frequency of the planet's spin nearly coincides with one of the precession frequencies of the ascending node of the planet's orbit. Using analytical expressions, we evaluated the obliquity variations of terrestrial planets with prograde spins in HZs. We found that the obliquity of terrestrial planets suffers large variations when the giant planet's orbit is separated by several Hill radii from an edge of the HZ, in which the orbits of the terrestrial planets in the HZ are marginally stable. Applying these results to the known extrasolar planetary systems, we found that about half of these systems can have terrestrial planets with small obliquity variations (smaller than 10°) over their entire HZs. However, the systems with both small obliquity variations and stable orbits in their HZs are only 1/5 of known systems. Most such systems are comprised of short-period giant planets. If additional planets are found in the known planetary systems, they generally tend to enhance the obliquity variations. On the other hand, if a large/close satellite exists, it significantly enhances the precession rate of the spin axis of a terrestrial planet and is likely to reduce the obliquity variations of the planet. Moreover, if a terrestrial planet is in a retrograde spin state, the spin-orbit resonance does not occur. Retrograde spin, or a large/close satellite might be essential for land-based life to survive on a terrestrial planet in an HZ.