The increased frequency and intensity of floods necessitate flood protection measures, traditionally canalization and the construction of levees. In addition, during the last decades, more flood retarding works such as dams and flood storage basins, have been built.
There are 34 large dans in the FRG (each with a volume of more than 8 million m3); twenty of them are used, among other purposes, for protection against floods. Innumerable flood
storage basins in the lower reaches of the rivers serve for recreation and fishing as well as for flood protection. A particular flood protection system will be chosen largely on economic grounds.
plain have been built upon. Subsequently levees have been built to protect the towns against flooding.
The intensive growth of urbanization, especially during the last 100 years, has necessi- tated considerable improvement of the dike system, along, for example, the lower Rhine. It has been shown that these measures aggravate the flood problem in the valley by reducing the
Many towns in Germany have developed in river valleys, where parts of the natural flood
. available storage. /-
For these reasons, under the new law regarding water management in the FRG, the flood plain areas have been designated. Those areas are not to be built on and must remain largely unchanged. Physical changes on major rivers are to be carried out only after extensive ex- periments, mainly with models, have been made to investigate their effects. Under the new water management law, such changes will be approved only after a public enquiry.
account the need to protect urban areas. There are no official regulations concerning the degree of safety (offered by flood protection measures) in the FRG.
populated areas such as the lower Rhine. Due to the expansion of urban areas, and in parti- cular industrial development, the need for protection has increased considerably during the last 100 years. Extensive modifications to old dikes had to be undertaken in respect of both profiles and height. For example, in the lower Rhine the design height of the dikes is based on a flood peak with a return period of 1000 years, plus an additional allowance for other influences such as wind, waves, and river diversions. Along the lower Rhine there are 350 km of dikes which are maintained and defended against floods by independent corporations under the supervision of the state.
The design frequency of flood protection works (dikes, storage basins, etc) takes into There is a long tradition of dike construction, especially in endangered and densely
11-1.9 WATER POLLUTION
The wastewater generated in the FRG in 1969 amounted to 45.63 million m per day, an annual 3 wastewater volume of about 16 O00 million m3 (Bundesminister des Innern, 1972a). A level of
28 O00 million m3 is expected by the year 2000 (Bundesminister des Innern, 1972b). At pres- ent about 20% of the surface runoff is from wastewater and it is expected that after 30 years about one-third of the natural water in rivers will be exploited, and that the greatest part of it will be returned to the rivers in the form of treated wastewater (Bundesminister des Innern, 1971).
The daily amount of wastewater generated, 45.63 million m3, does not inclùde cooling water discharged by public electric power plants, which amounted to about 34 million m3 per day in 1969, nor does it include recirculated water used in industry and power generation which amounted to 52.8 million m3 of water per day in 1969 (Bundesminister des Innern,l972a).
the FRG increased almost 48% between 1957 and 1969, (Bundesminister des Innern, 1972a). Dur- ing this period the pollution loads from fully biologically processed effluent (BOD5 reduc- tion more than 75%) have more than quadrupled, those from partially biologically processed effluent (BOD5 reduction less than 75%) have more than doubled, and those from untreated effluent have doubled; pollution from mechanically treated effluent has remained approxi- mately the same. (Bundesminister des Innern, 1972a).
erable funds to greatly accelerate improvements to and new construction of, effluent treat- ment plants.
crease even faster in future to reduce water pollution. Thus, the Federal Government's en- vironmental programme provides for 90% of the population to be connected to public sewerage systems by 1985, and that all treatment plants shall have a fully biological or equivalent process (Table LO). At present costs this will require annual investments of 1 100 million
Surveys show that the treated and untreated wastewater load carried by water courses in
Because of this increasing water pollution in the FRG, the government has spent consid- However, investment for the construction of sewage treatment plants must in-
Water
poZZution
Deutsche Marks for sewage treatment plants and 2 200 million Deutsche Marks for sewerage.
The introduction of large quantities of effluent into surface water bodies results in continuously increasing pollution. Thus, more than half of the surface water resources in the FRG are more than moderately polluted. Especially difficult loads are carried in areas of industrial concentration such as the lower Rhine, the Rhine-Main area, the Ludwigshafen- Mannheim metropolitan area, and the Stuttgart conurbation. Moreover, increasing water pol- lution is also observed where major cities are connected to rivers having low flows (such as Kassel on the Fulda River). A review of water pollution in the FRG is provided by Plate 1.
Increasing pollution of surface water constantly creates new problems where water supp- lies are obtained either directly from rivers or after filtration through the river banks.
This is because the great variety of harmful substances carried by the raw water is continu- ally increasing; hence water works have to employ increasingly advanced and sophisticated treatment processes to remove these harmful substances from the raw water. Sometimes this is very costly as, for example, for water works abstracting water from the Rhine River to supply the metropolitan areas of Cologne and Dusseldorf,
Hazards to the groundwater from abandoned gravel pits, poorly operated garbage dumps, and intensive application of fertilizer in agriculture are continually increasing. Moreover, the danger from drainage of hazardous liquids as a result of inadequate storage or accidents has become very severe. To protect areas located within the catchment area of water res- ources against hazards, water protection areas are established as required under the V?ater Act.
In addition to domestic and industrial sewage, environmental chemicals such as biocides, detergents and fertilizers, and toxic substances (toxides) have a very adverse effect on the natural self-purification capacity of surface waters. For example, it was found in 1967 that the natural self-purification capability of the lower Rhine River had been reduced by 30% as a result of toxides (Bundesminister des Tnnern, 1971). .
the 17.48 million m3/day of water drained via public sewerage in 1969, 49.8% was domestic sewage and sewage from small trade establishments, 36.9% consisted of industrial sewage,
(Bundesminister des Innern, 1972a) and 13.3% was groundwater or stream water. Of this daily quantity of effluent, 37.9% was treated by a fully biological process, 9.5% by a partial biological process, and 28.4% by a mechanical process, while 24.2% was drained without any treatment at all. The treatment of effluent generated via the public sewer system increas- ingly creates problems. Both domestic and industrial loads must be considered and their degree of treatment determined with greater accuracy.
million m3 per day.
cooling water. All this effluent, and 5.9% of other industrial effluent, was discharged into the rivers without treatment. Only 15.1% of industrial effluent was discharged into the rivers after treatment; however, the types and degree of this treatment are unknown.
(Bundesminister des Innern, 1972a). Industry is faced with especially difficult problems in the construction of treatment works as industrial wastewater has a frequently changing com- position, especially in the chemical and metal-proce’ssing industries.
The increasing application of fertilizer in agriculture results in more and more plant fertilizers (especially the nitrogen and phosphorus compounds) being leached from the soil and discharged into the rivers where they cause an increased growth of plant and animal organisms. The final result of this process is the accelerated eutrophication of the recip- ient water bodies.
The FRG is among the nations with the greatest application of mineral fertilizers. For example, a survey covering the period 1956-1970 showed that 69 kg of nitrogen and 60 kg of phosphorus were used per hectare of agricultural area (fields, meadows). (Bundesminister des Innern, 1972a).
in eutrophication of water masses. It has been estimated that a third of the phosphate input originates from leached fertilizer, a third is from human phosphorus metabolism, and the remaining third is from detergents. The high phosphate input originating from human meta- bolism (1/3) and from the use of detergents (1/3) by man must be taken into consideration, especially where settlements are located close to waters. Thus, in 1940, Lake Constance was entirely clean and was free of phosphorus;
Increasing water pollution affects not only the surface water but also the groundwater.
In the FRG wastewater is drained via either public or company-owned sewer systems. Of
In 1969, effluent discharge from the company-owned industrial sewer systems was 28.14 Of thisp15.7% was predominately saline mine water, while 63.3% was
This large input of phosphate is considered to be the primary cause of the acceleration
in 1964 the content was 50 mg of phosphorus per m3.
60
Plate 1. Degree of the pollution of surface waters in the Federal Republic of Germany in 1967.
61