· · · Repository Hydraulic Engineering Reports

Graphs with the daily discharge of the Rhine river.

De Kaderrichtlijn Water heeft tot doel de oppervlaktewateren - waaronder ook overgangswater en kustwater - en het grondwater in de Europese Unie te beschermen en te verbeteren en het duurzaam gebruik van water te bevorderen. De doelstellingen van de KRW moeten op 22 december 2015 zijn bereikt. Deze termijn kan onder bepaalde voorwaarden worden verlengd met maximaal twee periodes van zes jaar. De uiterste datum komt daarmee op 2027. De Kaderrichtlijn Water geeft voor alle landen in de Europese Unie een kader voor de bescherming en verbetering van de kwaliteit van het grond- en oppervlaktewater en van de kwantiteit van het grondwater. De richtlijn moedigt alle belanghebbenden aan om actief deel te nemen aan activiteiten om in ieders belang een goede waterkwaliteit te realiseren. Het stroomgebied Rijndelta omvat het gehele Nederlandse stroomgebied van de Rijn alsmede een klein deel van het Duitse oppervlak van het internationale stroomgebieddistrict Rijn. Het onderhavige plan betreft het Nederlandse deel van het stroomgebied Rijndelta met daarin onder meer een beschrijving van dit deel van het stroomgebied, de doelen voor de oppervlakteen grondwaterlichamen en een samenvatting van de maatregelen die genomen gaan worden.

Uitbreiding van het bestand van binnenvaartschepen met schepen groter dan het Groot Rijnschip, aanvulling met diepgang van die schepen

Maps of the Rhine section between Basel and Mainz including the flood defence system.

A few kilometres after crossing the Dutch frontier the Waal splits off from the river Rhine and flows to the left carrying 70% of the Rhine's water. A few kilometres further down, the IJssel splits off and flows to the right carrying 12% of the water coming down the Rhine. The river Rhine turns to the left carrying the remaining 18% of its original quantity. The river is then called Neder-Rijn (Lower Rhine) and after some 50 km westwards its name is changed into Lek. This must be regarded as Nature's distribution; the layout of the canals and cities, and the dimensions of dikes, sluices and bridges were all conditioned by it. On the other hand, the water coming down the river had to be put to the best possible use, so the flow had to be redistributed or at all events had to be made redistributable. The exigencies of both water management and inland shipping made a certain degree of regularisation desirable, particularly when the Rhine discharge was low. To meet the principal requirements, a scheme was worked out by Rijkswaterstaat (the Water Control and Public Works Department) which: a. when the discharge was either average or high would maintain the original distribution over the three branches; b. when the discharge was low would enable to control distribution of the Rhine's water between the Waal, IJssel and the Lower Rhine. When the discharge is low, the Lower Rhine is reduced to a temporary canal the discharge of which is controlled and the navigation depths of which are optimized by three sets ofweirs and locks. The scheme is known as the Lower Rhine canalization project. The Lower Rhine will be acting as a canal for six to nine months every year, depending on the natural regime of the river Rhine and on the exigencies of water management and transport. During the remaining period of higher discharges, when the arguments against artificial distribution prevail, the weirs will be raised, thus reinstating Nature's distribution ofthe discharge over the th ree branches.

Policy plans and subsequent measures to reduce nutrient concentrations in coastal waters require realistic historical information on nutrient concentrations. The main goal of the present report was to develop and apply a practical, but scientifically sound strategy to assess the background concentrations of nutrients in the Dutch Wadden Sea. Given the changes in the area (e .g. the closing of the former Zuiderzee) and the availabifity of only a restricted set of historical data, we decided to modify this goal in : the development and application of a practical hindcasting method to estimate nutrient concentrations that would have occurred in the Dutch Wadden Sea under the present conditions, given the nutrient concentrations in the rivers and in the adjacent North Sea in the period prior to the early 1930s. Two subtanks were defined : (1) the assessment of the nutrient concentrations in the adjacent North Sea area representing the period before circa 1930, as well as freshwater discharges, nutrient concentrations, and nutrient loads by the fresh water inputs to the Dutch Wadden Sea (2) the estimation of the seasonal fluctuations in the nutrient concentrations in the basins of the Dutch Wadden Sea. Considered were the river Rhine (at Lobith/Spijk), the river IJssel (at Kampen), the IJsselmeer, the Lauwersmeer, the river Ems, the Westerwoldsche Aa and the Eemskanaal. Attention was focused to the nutrients ammonium, nitrate, phosphate, total nitrogen and total phosphorus. Important steps in the calculation procedure were the assessment of freshwater discharge, the estimation of present and past nutrient concentrations in river water, the nutrient retention in between the rivers and the sea, the nutrient loads at freshwater discharge points and the assessment of the concentrations in the Wadden Sea prior to the early 1930s . Based on these calculation, the seasonal cycles in the phosphorus and nitrogen loads and concentrations at Den Oever and Kornwerderzand were assessed as welt as the seasonal cycles of the background phosphorus and nitrogen concentrations in the Dutch Wadden Sea.